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/components/chat/AttachmentPreview.tsx

@@ -0,0 +1,178 @@
+/**
+ * AttachmentPreview — рендер `Message.attachment` внутри bubble'а.
+ *
+ * Четыре формы:
+ *   - image → Image с object-fit cover, aspect-ratio из width/height
+ *   - video → то же + play-overlay в центре, duration внизу-справа
+ *   - voice → row [play-icon] [waveform stub] [duration]
+ *   - file  → row [file-icon] [name + size]
+ *
+ * Вложения размещаются ВНУТРИ того же bubble'а что и текст, чуть ниже
+ * footer'а нет и ширина bubble'а снимает maxWidth-ограничение ради
+ * изображений (отдельный media-first-bubble case).
+ */
+import React from 'react';
+import { View, Text, Image } from 'react-native';
+import { Ionicons } from '@expo/vector-icons';
+
+import type { Attachment } from '@/lib/types';
+import { VoicePlayer } from '@/components/chat/VoicePlayer';
+import { VideoCirclePlayer } from '@/components/chat/VideoCirclePlayer';
+
+export interface AttachmentPreviewProps {
+  attachment: Attachment;
+  /** Используется для тонирования footer-элементов. */
+  own?: boolean;
+}
+
+function formatSize(bytes: number): string {
+  if (bytes < 1024) return `${bytes} B`;
+  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(0)} KB`;
+  if (bytes < 1024 * 1024 * 1024) return `${(bytes / 1024 / 1024).toFixed(1)} MB`;
+  return `${(bytes / 1024 / 1024 / 1024).toFixed(2)} GB`;
+}
+
+function formatDuration(seconds: number): string {
+  const m = Math.floor(seconds / 60);
+  const s = Math.floor(seconds % 60);
+  return `${m}:${String(s).padStart(2, '0')}`;
+}
+
+export function AttachmentPreview({ attachment, own }: AttachmentPreviewProps) {
+  switch (attachment.kind) {
+    case 'image':
+      return <ImageAttachment att={attachment} />;
+    case 'video':
+      // circle=true — круглое видео-сообщение (Telegram-стиль).
+      return attachment.circle
+        ? <VideoCirclePlayer uri={attachment.uri} duration={attachment.duration} />
+        : <VideoAttachment att={attachment} />;
+    case 'voice':
+      return <VoicePlayer uri={attachment.uri} duration={attachment.duration} own={own} />;
+    case 'file':
+      return <FileAttachment att={attachment} own={own} />;
+  }
+}
+
+// ─── Image ──────────────────────────────────────────────────────────
+
+function ImageAttachment({ att }: { att: Attachment }) {
+  // Aspect-ratio из реальных width/height; fallback 4:3.
+  const aspect = att.width && att.height ? att.width / att.height : 4 / 3;
+  return (
+    <Image
+      source={{ uri: att.uri }}
+      style={{
+        width: '100%',
+        aspectRatio: aspect,
+        borderRadius: 12,
+        marginBottom: 4,
+        backgroundColor: '#0a0a0a',
+      }}
+      resizeMode="cover"
+    />
+  );
+}
+
+// ─── Video ──────────────────────────────────────────────────────────
+
+function VideoAttachment({ att }: { att: Attachment }) {
+  const aspect = att.width && att.height ? att.width / att.height : 16 / 9;
+  return (
+    <View style={{ position: 'relative', marginBottom: 4 }}>
+      <Image
+        source={{ uri: att.uri }}
+        style={{
+          width: '100%',
+          aspectRatio: aspect,
+          borderRadius: 12,
+          backgroundColor: '#0a0a0a',
+        }}
+        resizeMode="cover"
+      />
+      {/* Play overlay по центру */}
+      <View
+        style={{
+          position: 'absolute',
+          top: '50%', left: '50%',
+          transform: [{ translateX: -22 }, { translateY: -22 }],
+          width: 44, height: 44, borderRadius: 22,
+          backgroundColor: 'rgba(0,0,0,0.55)',
+          alignItems: 'center', justifyContent: 'center',
+        }}
+      >
+        <Ionicons name="play" size={22} color="#ffffff" style={{ marginLeft: 2 }} />
+      </View>
+      {att.duration !== undefined && (
+        <View
+          style={{
+            position: 'absolute',
+            right: 8, bottom: 8,
+            backgroundColor: 'rgba(0,0,0,0.6)',
+            paddingHorizontal: 6, paddingVertical: 2,
+            borderRadius: 4,
+          }}
+        >
+          <Text style={{ color: '#ffffff', fontSize: 11, fontWeight: '600' }}>
+            {formatDuration(att.duration)}
+          </Text>
+        </View>
+      )}
+    </View>
+  );
+}
+
+// ─── Voice ──────────────────────────────────────────────────────────
+// Реальный плеер — см. components/chat/VoicePlayer.tsx (expo-av Sound).
+
+// ─── File ───────────────────────────────────────────────────────────
+
+function FileAttachment({ att, own }: { att: Attachment; own?: boolean }) {
+  return (
+    <View
+      style={{
+        flexDirection: 'row',
+        alignItems: 'center',
+        marginBottom: 4,
+        gap: 10,
+        paddingVertical: 4,
+      }}
+    >
+      <View
+        style={{
+          width: 36, height: 36, borderRadius: 10,
+          backgroundColor: own ? 'rgba(255,255,255,0.18)' : '#1a1a1a',
+          alignItems: 'center', justifyContent: 'center',
+        }}
+      >
+        <Ionicons
+          name="document-text"
+          size={18}
+          color={own ? '#ffffff' : '#ffffff'}
+        />
+      </View>
+      <View style={{ flex: 1, minWidth: 0 }}>
+        <Text
+          numberOfLines={1}
+          style={{
+            color: '#ffffff',
+            fontSize: 14,
+            fontWeight: '600',
+          }}
+        >
+          {att.name ?? 'file'}
+        </Text>
+        <Text
+          style={{
+            color: own ? 'rgba(255,255,255,0.75)' : '#8b8b8b',
+            fontSize: 11,
+          }}
+        >
+          {att.size !== undefined ? formatSize(att.size) : ''}
+          {att.size !== undefined && att.mime ? '  ·  ' : ''}
+          {att.mime ?? ''}
+        </Text>
+      </View>
+    </View>
+  );
+}