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/(auth)/created.tsx

@@ -0,0 +1,196 @@
+/**
+ * Account Created confirmation screen — dark minimalist.
+ * Показывает адрес + x25519, кнопки copy и export (share) key.json.
+ */
+import React, { useState } from 'react';
+import { View, Text, ScrollView, Alert, Pressable, Share } from 'react-native';
+import { router } from 'expo-router';
+import * as Clipboard from 'expo-clipboard';
+import { Ionicons } from '@expo/vector-icons';
+import { useSafeAreaInsets } from 'react-native-safe-area-context';
+import { useStore } from '@/lib/store';
+
+import { Header } from '@/components/Header';
+
+export default function AccountCreatedScreen() {
+  const insets  = useSafeAreaInsets();
+  const keyFile = useStore(s => s.keyFile);
+  const [copied, setCopied] = useState<string | null>(null);
+
+  if (!keyFile) {
+    router.replace('/');
+    return null;
+  }
+
+  async function copy(value: string, label: string) {
+    await Clipboard.setStringAsync(value);
+    setCopied(label);
+    setTimeout(() => setCopied(null), 1800);
+  }
+
+  async function exportKey() {
+    try {
+      const json = JSON.stringify(keyFile, null, 2);
+      // Используем плоский Share API — без записи во временный файл.
+      // Получатель (mail, notes, etc.) получит текст целиком; юзер сам
+      // сохраняет как .json если нужно.
+      await Share.share({
+        message: json,
+        title:   'DChain key file',
+      });
+    } catch (e: any) {
+      Alert.alert('Export failed', e?.message ?? 'Unknown error');
+    }
+  }
+
+  return (
+    <View style={{ flex: 1, backgroundColor: '#000000', paddingTop: insets.top }}>
+      <Header title="Account created" />
+      <ScrollView contentContainerStyle={{ padding: 14, paddingBottom: 40 }}>
+        {/* Success badge */}
+        <View style={{ alignItems: 'center', marginTop: 10, marginBottom: 18 }}>
+          <View
+            style={{
+              width: 64, height: 64, borderRadius: 32,
+              backgroundColor: 'rgba(59,165,93,0.15)',
+              alignItems: 'center', justifyContent: 'center',
+              marginBottom: 10,
+            }}
+          >
+            <Ionicons name="checkmark" size={32} color="#3ba55d" />
+          </View>
+          <Text style={{ color: '#ffffff', fontSize: 20, fontWeight: '800' }}>
+            Welcome aboard
+          </Text>
+          <Text style={{ color: '#8b8b8b', fontSize: 13, marginTop: 6, textAlign: 'center' }}>
+            Keys have been generated and stored securely.
+          </Text>
+        </View>
+
+        {/* Address */}
+        <KeyCard
+          title="Your address (Ed25519)"
+          value={keyFile.pub_key}
+          copied={copied === 'address'}
+          onCopy={() => copy(keyFile.pub_key, 'address')}
+        />
+
+        {/* X25519 */}
+        <View style={{ height: 10 }} />
+        <KeyCard
+          title="Encryption key (X25519)"
+          value={keyFile.x25519_pub}
+          copied={copied === 'x25519'}
+          onCopy={() => copy(keyFile.x25519_pub, 'x25519')}
+        />
+
+        {/* Backup */}
+        <View
+          style={{
+            marginTop: 16,
+            padding: 14,
+            borderRadius: 14,
+            backgroundColor: 'rgba(240,179,90,0.08)',
+            borderWidth: 1, borderColor: 'rgba(240,179,90,0.25)',
+          }}
+        >
+          <View style={{ flexDirection: 'row', alignItems: 'center', marginBottom: 6 }}>
+            <Ionicons name="lock-closed-outline" size={14} color="#f0b35a" />
+            <Text style={{ color: '#f0b35a', fontSize: 13, fontWeight: '700', marginLeft: 6 }}>
+              Backup your key file
+            </Text>
+          </View>
+          <Text style={{ color: '#d0a26a', fontSize: 12, lineHeight: 17, marginBottom: 10 }}>
+            Export it now and store somewhere safe — password managers, cold
+            storage, printed paper. If you lose it, you lose the account.
+          </Text>
+          <Pressable
+            onPress={exportKey}
+            style={({ pressed }) => ({
+              alignItems: 'center', justifyContent: 'center',
+              paddingVertical: 10, borderRadius: 999,
+              backgroundColor: pressed ? '#2a1f0f' : '#1a1409',
+              borderWidth: 1, borderColor: 'rgba(240,179,90,0.35)',
+            })}
+          >
+            <Text style={{ color: '#f0b35a', fontWeight: '700', fontSize: 14 }}>
+              Export key.json
+            </Text>
+          </Pressable>
+        </View>
+
+        {/* Continue */}
+        <Pressable
+          onPress={() => router.replace('/(app)/chats' as never)}
+          style={({ pressed }) => ({
+            alignItems: 'center', justifyContent: 'center',
+            paddingVertical: 14, borderRadius: 999, marginTop: 20,
+            backgroundColor: pressed ? '#1a8cd8' : '#1d9bf0',
+          })}
+        >
+          <Text style={{ color: '#ffffff', fontWeight: '700', fontSize: 15 }}>
+            Open messenger
+          </Text>
+        </Pressable>
+      </ScrollView>
+    </View>
+  );
+}
+
+function KeyCard({
+  title, value, copied, onCopy,
+}: {
+  title: string;
+  value: string;
+  copied: boolean;
+  onCopy: () => void;
+}) {
+  return (
+    <View
+      style={{
+        borderRadius: 14,
+        backgroundColor: '#0a0a0a',
+        borderWidth: 1, borderColor: '#1f1f1f',
+        padding: 14,
+      }}
+    >
+      <Text
+        style={{
+          color: '#5a5a5a', fontSize: 11, fontWeight: '700',
+          textTransform: 'uppercase', letterSpacing: 1.2, marginBottom: 8,
+        }}
+      >
+        {title}
+      </Text>
+      <Text style={{ color: '#ffffff', fontSize: 12, fontFamily: 'monospace', lineHeight: 18 }}>
+        {value}
+      </Text>
+      <Pressable
+        onPress={onCopy}
+        style={({ pressed }) => ({
+          flexDirection: 'row',
+          alignItems: 'center',
+          justifyContent: 'center',
+          paddingVertical: 9, borderRadius: 999,
+          marginTop: 10,
+          backgroundColor: pressed ? '#1a1a1a' : '#111111',
+          borderWidth: 1, borderColor: '#1f1f1f',
+        })}
+      >
+        <Ionicons
+          name={copied ? 'checkmark' : 'copy-outline'}
+          size={14}
+          color={copied ? '#3ba55d' : '#ffffff'}
+        />
+        <Text
+          style={{
+            color: copied ? '#3ba55d' : '#ffffff',
+            fontSize: 13, fontWeight: '600', marginLeft: 6,
+          }}
+        >
+          {copied ? 'Copied' : 'Copy'}
+        </Text>
+      </Pressable>
+    </View>
+  );
+}