feat(client): Twitter-style social feed UI (Phase C of v2.0.0)

Ships the client side of the v2.0.0 feed feature. Folds client-app/
into the monorepo (was previously .gitignored as "tracked separately"
but no separate repo ever existed — for v2.0.0 the client is
first-class).

Feed screens

  app/(app)/feed.tsx — Feed tab
    - Three-way tab strip: Подписки / Для вас / В тренде backed by
      /feed/timeline, /feed/foryou, /feed/trending respectively
    - Default landing tab is "Для вас" — surfaces discovery without
      requiring the user to follow anyone first
    - FlatList with pull-to-refresh + viewability-driven view counter
      bump (posts visible ≥ 60% for ≥ 1s trigger POST /feed/post/…/view)
    - Floating blue compose button → /compose
    - Per-post liked_by_me fetched in batches of 6 after list load

  app/(app)/compose.tsx — post composer modal
    - Fullscreen, Twitter-like header (✕ left, Опубликовать right)
    - Auto-focused multiline TextInput, 4000 char cap
    - Hashtag preview chips that auto-update as you type
    - expo-image-picker + expo-image-manipulator pipeline: resize to
      1080px max-dim, JPEG Q=50 (client-side first-pass compression
      before the mandatory server-side scrub)
    - Live fee estimate + balance guard with a confirmation modal
      ("Опубликовать пост? Цена: 0.00X T · Размер: N KB")
    - Exif: false passed to ImagePicker as an extra privacy layer

  app/(app)/feed/[id].tsx — post detail
    - Full PostCard rendering + detailed info panel (views, likes,
      size, fee, hosting relay, hashtags as tappable chips)
    - Triggers bumpView on mount
    - 410 (on-chain soft-delete) routes back to the feed

  app/(app)/feed/tag/[tag].tsx — hashtag feed

  app/(app)/profile/[address].tsx — rebuilt
    - Twitter-ish profile: avatar, name, address short-form, post count
    - Posts | Инфо tab strip
    - Follow / Unfollow button for non-self profiles (optimistic UI)
    - Edit button on self profile → settings
    - Secondary actions (chat, copy address) when viewing a known contact

Supporting library

  lib/feed.ts — HTTP wrappers + tx builders for every /feed/* endpoint:
    - publishPost (POST /feed/publish, signed)
    - publishAndCommit (publish → on-chain CREATE_POST)
    - fetchPost / fetchStats / bumpView
    - fetchAuthorPosts / fetchTimeline / fetchForYou / fetchTrending /
      fetchHashtag
    - buildCreatePostTx / buildDeletePostTx
    - buildFollowTx / buildUnfollowTx
    - buildLikePostTx / buildUnlikePostTx
    - likePost / unlikePost / followUser / unfollowUser / deletePost
      (high-level helpers that bundle build + submitTx)
    - formatFee, formatRelativeTime, formatCount — Twitter-like display
      helpers

  components/feed/PostCard.tsx — core card component
    - Memoised for performance (N-row re-render on every like elsewhere
      would cost a lot otherwise)
    - Optimistic like toggle with heart-bounce spring animation
    - Hashtag highlighting in body text (tappable → hashtag feed)
    - Long-press context menu (Delete, owner-only)
    - Views / likes / share-link / reply icons in footer row

Navigation cleanup

  - NavBar: removed the SOON pill on the Feed tab (it's shipped now)
  - (app)/_layout: hide NavBar on /compose and /feed/* sub-routes
  - AnimatedSlot: treat /feed/<id>, /feed/tag/<t>, /compose as
    sub-routes so back-swipe-right closes them

Channel removal (client side)

  - lib/types.ts: ContactKind stripped to 'direct' | 'group'; legacy
    'channel' flag removed. `kind` field kept for backward compat with
    existing AsyncStorage records.
  - lib/devSeed.ts: dropped the 5 channel seed contacts.
  - components/ChatTile.tsx: removed channel kindIcon branch.

Dependencies

  - expo-image-manipulator added for client-side image compression.
  - expo-file-system/legacy used for readAsStringAsync (SDK 54 moved
    that API to the legacy sub-path; the new streaming API isn't yet
    stable).

Type check

  - npx tsc --noEmit — clean, 0 errors.

Next (not in this commit)

  - Direct attachment-bytes endpoint on the server so post-detail can
    actually render the image (currently shows placeholder with URL)
  - Cross-relay body fetch via /api/relays + hosting_relay pubkey
  - Mentions (@username) with notifications
  - Full-text search

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

client-app/app/index.tsx

@@ -0,0 +1,519 @@
+/**
+ * Onboarding — 3-слайдовый pager перед auth-экранами.
+ *
+ * Slide 1 — "Why DChain": value-proposition, 3 пункта с иконками.
+ * Slide 2 — "How it works": выбор релей-ноды (public paid vs свой node),
+ *           ссылка на Gitea, + node URL input с live ping.
+ * Slide 3 — "Your keys": кнопки Create / Import.
+ *
+ * Если `keyFile` в store уже есть (bootstrap из RootLayout загрузил) —
+ * делаем <Redirect /> в (app), чтобы пользователь не видел вообще никакого
+ * мелькания onboarding'а. До загрузки `booted === false` root показывает
+ * чёрный экран.
+ */
+import React, { useEffect, useState, useCallback, useRef } from 'react';
+import {
+  View, Text, TextInput, Pressable, ScrollView,
+  Alert, ActivityIndicator, Linking, Dimensions,
+  useWindowDimensions,
+} from 'react-native';
+import { router, Redirect } from 'expo-router';
+import { Ionicons } from '@expo/vector-icons';
+import { CameraView, useCameraPermissions } from 'expo-camera';
+import { useSafeAreaInsets } from 'react-native-safe-area-context';
+import { useStore } from '@/lib/store';
+import { saveSettings } from '@/lib/storage';
+import { setNodeUrl, getNetStats } from '@/lib/api';
+
+const { width: SCREEN_W } = Dimensions.get('window');
+const GITEA_URL = 'https://git.vsecoder.vodka/vsecoder/dchain';
+
+export default function WelcomeScreen() {
+  const insets      = useSafeAreaInsets();
+  const { height: SCREEN_H } = useWindowDimensions();
+  const keyFile     = useStore(s => s.keyFile);
+  const booted      = useStore(s => s.booted);
+  const settings    = useStore(s => s.settings);
+  const setSettings = useStore(s => s.setSettings);
+
+  const scrollRef = useRef<ScrollView>(null);
+  const [page, setPage]           = useState(0);
+  const [nodeInput, setNodeInput] = useState('');
+  const [scanning,  setScanning]  = useState(false);
+  const [checking,  setChecking]  = useState(false);
+  const [nodeOk,    setNodeOk]    = useState<boolean | null>(null);
+
+  const [permission, requestPermission] = useCameraPermissions();
+
+  useEffect(() => { setNodeInput(settings.nodeUrl); }, [settings.nodeUrl]);
+
+  // ВСЕ hooks должны быть объявлены ДО любого early-return, иначе
+  // React на следующем render'е посчитает разное число hooks и выкинет
+  // "Rendered fewer hooks than expected". useCallback ниже — тоже hook.
+  const applyNode = useCallback(async (url: string) => {
+    const clean = url.trim().replace(/\/$/, '');
+    if (!clean) return;
+    setChecking(true);
+    setNodeOk(null);
+    setNodeUrl(clean);
+    try {
+      await getNetStats();
+      setNodeOk(true);
+      const next = { ...settings, nodeUrl: clean };
+      setSettings(next);
+      await saveSettings(next);
+    } catch {
+      setNodeOk(false);
+    } finally {
+      setChecking(false);
+    }
+  }, [settings, setSettings]);
+
+  const onQrScanned = useCallback(({ data }: { data: string }) => {
+    setScanning(false);
+    let url = data.trim();
+    try { const p = JSON.parse(url); if (p.nodeUrl) url = p.nodeUrl; } catch {}
+    setNodeInput(url);
+    applyNode(url);
+  }, [applyNode]);
+
+  // Bootstrap ещё не закончился — ничего не рендерим, RootLayout покажет
+  // чёрный экран (single source of truth для splash-state'а).
+  if (!booted) return null;
+
+  // Ключи уже загружены — сразу в main app, без мелькания onboarding'а.
+  if (keyFile) return <Redirect href={'/(app)/chats' as never} />;
+
+  const openScanner = async () => {
+    if (!permission?.granted) {
+      const { granted } = await requestPermission();
+      if (!granted) {
+        Alert.alert('Camera permission required', 'Allow camera access to scan QR codes.');
+        return;
+      }
+    }
+    setScanning(true);
+  };
+
+  const goToPage = (p: number) => {
+    scrollRef.current?.scrollTo({ x: p * SCREEN_W, animated: true });
+    setPage(p);
+  };
+
+  if (scanning) {
+    return (
+      <View style={{ flex: 1, backgroundColor: '#000' }}>
+        <CameraView
+          style={{ flex: 1 }}
+          facing="back"
+          barcodeScannerSettings={{ barcodeTypes: ['qr'] }}
+          onBarcodeScanned={onQrScanned}
+        />
+        <View style={{
+          position: 'absolute', top: 0, left: 0, right: 0, bottom: 0,
+          alignItems: 'center', justifyContent: 'center',
+        }}>
+          <View style={{ width: 240, height: 240, borderWidth: 2, borderColor: '#fff', borderRadius: 16 }} />
+          <Text style={{ color: '#fff', marginTop: 20, opacity: 0.8 }}>
+            Point at a DChain node QR code
+          </Text>
+        </View>
+        <Pressable
+          onPress={() => setScanning(false)}
+          style={{
+            position: 'absolute', top: 56, left: 16,
+            backgroundColor: 'rgba(0,0,0,0.6)', borderRadius: 20,
+            paddingHorizontal: 16, paddingVertical: 8,
+          }}
+        >
+          <Text style={{ color: '#fff', fontSize: 16 }}>✕  Cancel</Text>
+        </Pressable>
+      </View>
+    );
+  }
+
+  const statusColor = nodeOk === true ? '#3ba55d' : nodeOk === false ? '#f4212e' : '#8b8b8b';
+
+  // Высота footer'а (dots + inset) — резервируем под неё снизу каждого
+  // слайда, чтобы CTA-кнопки оказывались прямо над индикатором страниц,
+  // а не залезали под него.
+  const FOOTER_H = Math.max(insets.bottom, 20) + 8 + 12 + 7; // = padBottom + padTop + dot
+  const PAGE_H   = SCREEN_H - FOOTER_H;
+
+  return (
+    <View style={{ flex: 1, backgroundColor: '#000000' }}>
+      <ScrollView
+        ref={scrollRef}
+        horizontal
+        pagingEnabled
+        showsHorizontalScrollIndicator={false}
+        onMomentumScrollEnd={e => {
+          const p = Math.round(e.nativeEvent.contentOffset.x / SCREEN_W);
+          setPage(p);
+        }}
+        style={{ flex: 1 }}
+        keyboardShouldPersistTaps="handled"
+      >
+        {/* ───────── Slide 1: Why DChain ───────── */}
+        <View style={{ width: SCREEN_W, height: PAGE_H }}>
+          <ScrollView
+            style={{ flex: 1 }}
+            contentContainerStyle={{
+              paddingHorizontal: 28,
+              paddingTop: insets.top + 60,
+              paddingBottom: 16,
+            }}
+            showsVerticalScrollIndicator={false}
+          >
+            <View style={{ alignItems: 'center', marginBottom: 36 }}>
+              <View
+                style={{
+                  width: 88, height: 88, borderRadius: 24,
+                  backgroundColor: '#1d9bf0',
+                  alignItems: 'center', justifyContent: 'center',
+                  marginBottom: 14,
+                }}
+              >
+                <Ionicons name="chatbubbles" size={44} color="#ffffff" />
+              </View>
+              <Text style={{ color: '#ffffff', fontSize: 30, fontWeight: '800', letterSpacing: -0.8 }}>
+                DChain
+              </Text>
+              <Text style={{ color: '#8b8b8b', textAlign: 'center', fontSize: 14, lineHeight: 20, marginTop: 6 }}>
+                A messenger that belongs to you.
+              </Text>
+            </View>
+
+            <FeatureRow
+              icon="lock-closed"
+              title="End-to-end encryption"
+              text="X25519 + NaCl на каждом сообщении. Даже релей-нода не может прочитать переписку."
+            />
+            <FeatureRow
+              icon="key"
+              title="Твои ключи — твой аккаунт"
+              text="Без телефона, email и серверных паролей. Ключи никогда не покидают устройство."
+            />
+            <FeatureRow
+              icon="git-network"
+              title="Decentralised"
+              text="Любой может поднять свою ноду. Нет единой точки отказа и цензуры."
+            />
+          </ScrollView>
+
+          {/* CTA — прижата к правому нижнему краю. */}
+          <View style={{
+            flexDirection: 'row', justifyContent: 'flex-end',
+            paddingHorizontal: 24, paddingBottom: 8,
+          }}>
+            <CTAPrimary label="Продолжить" onPress={() => goToPage(1)} />
+          </View>
+        </View>
+
+        {/* ───────── Slide 2: How it works ───────── */}
+        <View style={{ width: SCREEN_W, height: PAGE_H }}>
+          <ScrollView
+            style={{ flex: 1 }}
+            contentContainerStyle={{
+              paddingHorizontal: 28,
+              paddingTop: insets.top + 40,
+              paddingBottom: 16,
+            }}
+            showsVerticalScrollIndicator={false}
+            keyboardShouldPersistTaps="handled"
+          >
+          <Text style={{ color: '#ffffff', fontSize: 24, fontWeight: '800', letterSpacing: -0.5 }}>
+            Как это работает
+          </Text>
+          <Text style={{ color: '#8b8b8b', fontSize: 14, lineHeight: 20, marginTop: 8, marginBottom: 22 }}>
+            Сообщения проходят через релей-ноду в зашифрованном виде.
+            Выбери публичную или подключи свою.
+          </Text>
+
+          <OptionCard
+            icon="globe"
+            title="Публичная нода"
+            text="Удобно и быстро — нода хостится комьюнити, небольшая комиссия за каждое отправленное сообщение."
+          />
+          <OptionCard
+            icon="hardware-chip"
+            title="Своя нода"
+            text="Максимальный контроль. Исходники открыты — подними на своём сервере за 5 минут."
+          />
+
+          <Text style={{
+            color: '#5a5a5a', fontSize: 11, fontWeight: '700',
+            textTransform: 'uppercase', letterSpacing: 1.2, marginTop: 20, marginBottom: 8,
+          }}>
+            Node URL
+          </Text>
+          <View style={{ flexDirection: 'row', gap: 8 }}>
+            <View
+              style={{
+                flex: 1, flexDirection: 'row', alignItems: 'center',
+                backgroundColor: '#0a0a0a', borderWidth: 1, borderColor: '#1f1f1f',
+                borderRadius: 12, paddingHorizontal: 12, gap: 8,
+              }}
+            >
+              <View style={{ width: 7, height: 7, borderRadius: 3.5, backgroundColor: statusColor }} />
+              <TextInput
+                value={nodeInput}
+                onChangeText={t => { setNodeInput(t); setNodeOk(null); }}
+                onEndEditing={() => applyNode(nodeInput)}
+                onSubmitEditing={() => applyNode(nodeInput)}
+                placeholder="http://192.168.1.10:8080"
+                placeholderTextColor="#5a5a5a"
+                autoCapitalize="none"
+                autoCorrect={false}
+                keyboardType="url"
+                returnKeyType="done"
+                style={{ flex: 1, color: '#ffffff', fontSize: 14, paddingVertical: 12 }}
+              />
+              {checking
+                ? <ActivityIndicator size="small" color="#8b8b8b" />
+                : nodeOk === true
+                  ? <Ionicons name="checkmark" size={16} color="#3ba55d" />
+                  : nodeOk === false
+                    ? <Ionicons name="close" size={16} color="#f4212e" />
+                    : null}
+            </View>
+            <Pressable
+              onPress={openScanner}
+              style={({ pressed }) => ({
+                width: 48, alignItems: 'center', justifyContent: 'center',
+                backgroundColor: pressed ? '#1a1a1a' : '#0a0a0a',
+                borderWidth: 1, borderColor: '#1f1f1f',
+                borderRadius: 12,
+              })}
+            >
+              <Ionicons name="qr-code-outline" size={22} color="#ffffff" />
+            </Pressable>
+          </View>
+          {nodeOk === false && (
+            <Text style={{ color: '#f4212e', fontSize: 12, marginTop: 6 }}>
+              Cannot reach node — check URL and that the node is running
+            </Text>
+          )}
+          </ScrollView>
+
+          {/* CTA — прижата к правому нижнему краю. */}
+          <View style={{
+            flexDirection: 'row', justifyContent: 'flex-end', gap: 10,
+            paddingHorizontal: 24, paddingBottom: 8,
+          }}>
+            <CTASecondary
+              label="Исходники"
+              icon="logo-github"
+              onPress={() => Linking.openURL(GITEA_URL).catch(() => {})}
+            />
+            <CTAPrimary label="Продолжить" onPress={() => goToPage(2)} />
+          </View>
+        </View>
+
+        {/* ───────── Slide 3: Your keys ───────── */}
+        <View style={{ width: SCREEN_W, height: PAGE_H }}>
+          <ScrollView
+            style={{ flex: 1 }}
+            contentContainerStyle={{
+              paddingHorizontal: 28,
+              paddingTop: insets.top + 60,
+              paddingBottom: 16,
+            }}
+            showsVerticalScrollIndicator={false}
+          >
+            <View style={{ alignItems: 'center', marginBottom: 36 }}>
+              <View
+                style={{
+                  width: 88, height: 88, borderRadius: 24,
+                  backgroundColor: '#0a0a0a',
+                  borderWidth: 1, borderColor: '#1f1f1f',
+                  alignItems: 'center', justifyContent: 'center',
+                  marginBottom: 16,
+                }}
+              >
+                <Ionicons name="key" size={44} color="#1d9bf0" />
+              </View>
+              <Text style={{ color: '#ffffff', fontSize: 24, fontWeight: '800', letterSpacing: -0.5, textAlign: 'center' }}>
+                Твой аккаунт
+              </Text>
+              <Text style={{ color: '#8b8b8b', fontSize: 14, lineHeight: 20, marginTop: 8, textAlign: 'center', maxWidth: 280 }}>
+                Создай новую пару ключей или импортируй существующую.
+                Ключи хранятся только на этом устройстве.
+              </Text>
+            </View>
+          </ScrollView>
+
+          {/* CTA — прижата к правому нижнему краю. */}
+          <View style={{
+            flexDirection: 'row', justifyContent: 'flex-end', gap: 10,
+            paddingHorizontal: 24, paddingBottom: 8,
+          }}>
+            <CTASecondary
+              label="Импорт"
+              onPress={() => router.push('/(auth)/import' as never)}
+            />
+            <CTAPrimary
+              label="Создать аккаунт"
+              onPress={() => router.push('/(auth)/create' as never)}
+            />
+          </View>
+        </View>
+      </ScrollView>
+
+      {/* Footer: dots-only pager indicator. CTA-кнопки теперь inline
+          на каждом слайде, чтобы выглядели как полноценные кнопки, а не
+          мелкий "Далее" в углу. */}
+      <View style={{
+        paddingHorizontal: 28,
+        paddingBottom: Math.max(insets.bottom, 20) + 8,
+        paddingTop: 12,
+        flexDirection: 'row',
+        alignItems: 'center', justifyContent: 'center',
+        gap: 6,
+      }}>
+        {[0, 1, 2].map(i => (
+          <Pressable
+            key={i}
+            onPress={() => goToPage(i)}
+            hitSlop={8}
+            style={{
+              width:  page === i ? 22 : 7,
+              height: 7,
+              borderRadius: 3.5,
+              backgroundColor: page === i ? '#1d9bf0' : '#2a2a2a',
+            }}
+          />
+        ))}
+      </View>
+    </View>
+  );
+}
+
+// ───────── helper components ─────────
+
+/**
+ * Primary CTA button — синий pill. Натуральная ширина (hugs content),
+ * `numberOfLines={1}` на лейбле чтобы текст не переносился. Фон
+ * применяется через inner View, а не напрямую на Pressable — это
+ * обходит редкие RN-баги, когда backgroundColor на Pressable не
+ * рендерится пока кнопка не нажата.
+ */
+function CTAPrimary({ label, onPress }: { label: string; onPress: () => void }) {
+  return (
+    <Pressable onPress={onPress} style={({ pressed }) => ({ opacity: pressed ? 0.85 : 1 })}>
+      <View
+        style={{
+          height: 46,
+          paddingHorizontal: 22,
+          borderRadius: 999,
+          backgroundColor: '#1d9bf0',
+          alignItems: 'center', justifyContent: 'center',
+        }}
+      >
+        <Text
+          numberOfLines={1}
+          style={{ color: '#ffffff', fontWeight: '700', fontSize: 15 }}
+        >
+          {label}
+        </Text>
+      </View>
+    </Pressable>
+  );
+}
+
+/** Secondary CTA — тёмный pill с border'ом, optional icon слева. */
+function CTASecondary({
+  label, icon, onPress,
+}: {
+  label: string;
+  icon?: React.ComponentProps<typeof Ionicons>['name'];
+  onPress: () => void;
+}) {
+  return (
+    <Pressable onPress={onPress} style={({ pressed }) => ({ opacity: pressed ? 0.6 : 1 })}>
+      <View
+        style={{
+          height: 46,
+          paddingHorizontal: 18,
+          borderRadius: 999,
+          backgroundColor: '#0a0a0a',
+          borderWidth: 1, borderColor: '#1f1f1f',
+          flexDirection: 'row', alignItems: 'center', justifyContent: 'center',
+          gap: 6,
+        }}
+      >
+        {icon && <Ionicons name={icon} size={15} color="#ffffff" />}
+        <Text
+          numberOfLines={1}
+          style={{ color: '#ffffff', fontWeight: '700', fontSize: 14 }}
+        >
+          {label}
+        </Text>
+      </View>
+    </Pressable>
+  );
+}
+
+function FeatureRow({
+  icon, title, text,
+}: { icon: React.ComponentProps<typeof Ionicons>['name']; title: string; text: string }) {
+  return (
+    <View style={{ flexDirection: 'row', marginBottom: 20, gap: 14 }}>
+      <View
+        style={{
+          width: 40, height: 40, borderRadius: 12,
+          backgroundColor: '#0a0a0a',
+          borderWidth: 1, borderColor: '#1f1f1f',
+          alignItems: 'center', justifyContent: 'center',
+        }}
+      >
+        <Ionicons name={icon} size={20} color="#1d9bf0" />
+      </View>
+      <View style={{ flex: 1 }}>
+        <Text style={{ color: '#ffffff', fontSize: 15, fontWeight: '700', marginBottom: 3 }}>
+          {title}
+        </Text>
+        <Text style={{ color: '#8b8b8b', fontSize: 13, lineHeight: 19 }}>
+          {text}
+        </Text>
+      </View>
+    </View>
+  );
+}
+
+function OptionCard({
+  icon, title, text, actionLabel, onAction,
+}: {
+  icon: React.ComponentProps<typeof Ionicons>['name'];
+  title: string;
+  text: string;
+  actionLabel?: string;
+  onAction?: () => void;
+}) {
+  return (
+    <View
+      style={{
+        backgroundColor: '#0a0a0a',
+        borderWidth: 1, borderColor: '#1f1f1f',
+        borderRadius: 14, padding: 14, marginBottom: 10,
+      }}
+    >
+      <View style={{ flexDirection: 'row', alignItems: 'center', gap: 10, marginBottom: 6 }}>
+        <Ionicons name={icon} size={18} color="#1d9bf0" />
+        <Text style={{ color: '#ffffff', fontSize: 15, fontWeight: '700' }}>
+          {title}
+        </Text>
+      </View>
+      <Text style={{ color: '#8b8b8b', fontSize: 13, lineHeight: 19 }}>
+        {text}
+      </Text>
+      {actionLabel && onAction && (
+        <Pressable onPress={onAction} style={({ pressed }) => ({ opacity: pressed ? 0.6 : 1, marginTop: 8 })}>
+          <Text style={{ color: '#1d9bf0', fontSize: 13, fontWeight: '600' }}>
+            {actionLabel}
+          </Text>
+        </Pressable>
+      )}
+    </View>
+  );
+}