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/(app)/chats/index.tsx

@@ -0,0 +1,105 @@
+/**
+ * Messages screen — список чатов в стиле референса.
+ *
+ *   ┌ safe-area top
+ *   │ TabHeader (title зависит от connection state)
+ *   │ ─ FlatList (chat tiles) ─
+ *   └ NavBar (external)
+ *
+ * Фильтры и search убраны — лист один поток; requests доступны через
+ * NavBar → notifications tab. FAB composer'а тоже убран (чат-лист
+ * просто отражает существующие беседы, создание новых — через tab
+ * "New chat" в NavBar'е).
+ */
+import React, { useMemo } from 'react';
+import { View, Text, FlatList } from 'react-native';
+import { router } from 'expo-router';
+import { Ionicons } from '@expo/vector-icons';
+import { useSafeAreaInsets } from 'react-native-safe-area-context';
+
+import { useStore } from '@/lib/store';
+import { useConnectionStatus } from '@/hooks/useConnectionStatus';
+import type { Contact, Message } from '@/lib/types';
+
+import { TabHeader }  from '@/components/TabHeader';
+import { ChatTile }   from '@/components/ChatTile';
+
+export default function ChatsScreen() {
+  const insets   = useSafeAreaInsets();
+  const contacts = useStore(s => s.contacts);
+  const messages = useStore(s => s.messages);
+
+  // Статус подключения: online / connecting / offline.
+  // Название шапки и цвет pip'а на аватаре зависят от него.
+  const connStatus = useConnectionStatus();
+
+  const headerTitle =
+    connStatus === 'online'     ? 'Messages' :
+    connStatus === 'connecting' ? 'Connecting…' :
+                                  'Waiting for internet';
+
+  const dotColor =
+    connStatus === 'online'     ? '#3ba55d' :   // green
+    connStatus === 'connecting' ? '#f0b35a' :   // amber
+                                  '#f4212e';    // red
+
+  const lastOf = (c: Contact): Message | null => {
+    const msgs = messages[c.address];
+    return msgs && msgs.length ? msgs[msgs.length - 1] : null;
+  };
+
+  // Сортировка по последней активности.
+  const sorted = useMemo(() => {
+    return [...contacts]
+      .map(c => ({ c, last: lastOf(c) }))
+      .sort((a, b) => {
+        const ka = a.last ? a.last.timestamp : a.c.addedAt / 1000;
+        const kb = b.last ? b.last.timestamp : b.c.addedAt / 1000;
+        return kb - ka;
+      })
+      .map(x => x.c);
+  }, [contacts, messages]);
+
+  return (
+    <View style={{ flex: 1, backgroundColor: '#000000', paddingTop: insets.top }}>
+      <TabHeader title={headerTitle} profileDotColor={dotColor} />
+
+      <View style={{ flex: 1 }}>
+        <FlatList
+          data={sorted}
+          keyExtractor={c => c.address}
+          renderItem={({ item }) => (
+            <ChatTile
+              contact={item}
+              lastMessage={lastOf(item)}
+              onPress={() => router.push(`/(app)/chats/${item.address}` as never)}
+            />
+          )}
+          contentContainerStyle={{ paddingBottom: 40, flexGrow: 1 }}
+          showsVerticalScrollIndicator={false}
+        />
+
+        {sorted.length === 0 && (
+          <View
+            pointerEvents="box-none"
+            style={{
+              position: 'absolute',
+              left: 0, right: 0, top: 0, bottom: 0,
+              alignItems: 'center',
+              justifyContent: 'center',
+              paddingHorizontal: 32,
+            }}
+          >
+            <Ionicons name="chatbubbles-outline" size={42} color="#3a3a3a" style={{ marginBottom: 10 }} />
+            <Text style={{ color: '#ffffff', fontSize: 16, fontWeight: '700', marginBottom: 6 }}>
+              No chats yet
+            </Text>
+            <Text style={{ color: '#8b8b8b', fontSize: 13, textAlign: 'center', lineHeight: 20 }}>
+              Use the search tab in the navbar to add your first contact.
+            </Text>
+          </View>
+        )}
+      </View>
+    </View>
+  );
+}