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/lib/dates.ts

@@ -0,0 +1,67 @@
+/**
+ * Date / time форматирование для UI мессенджера.
+ *
+ * Все функции принимают **unix-seconds** (совместимо с `Message.timestamp`,
+ * который тоже в секундах). Для ms-таймштампов делаем нормализацию внутри.
+ */
+
+// ─── Русские месяцы (genitive для "17 июня 2025") ────────────────────────────
+const RU_MONTHS_GEN = [
+  'января', 'февраля', 'марта',  'апреля', 'мая',     'июня',
+  'июля',   'августа', 'сентября', 'октября', 'ноября', 'декабря',
+];
+
+function sameDay(a: Date, b: Date): boolean {
+  return (
+    a.getFullYear() === b.getFullYear() &&
+    a.getMonth()    === b.getMonth()    &&
+    a.getDate()     === b.getDate()
+  );
+}
+
+/**
+ * Day-bucket label для сепараторов внутри чата.
+ *   "Сегодня" / "Вчера" / "17 июня 2025"
+ *
+ * @param ts unix-seconds
+ */
+export function dateBucket(ts: number): string {
+  const d = new Date(ts * 1000);
+  const now = new Date();
+  const yday = new Date(); yday.setDate(now.getDate() - 1);
+  if (sameDay(d, now))  return 'Сегодня';
+  if (sameDay(d, yday)) return 'Вчера';
+  return `${d.getDate()} ${RU_MONTHS_GEN[d.getMonth()]} ${d.getFullYear()}`;
+}
+
+/**
+ * Короткое relative-time под углом bubble ("29m", "14m", "3h", "2d", "12:40").
+ *
+ * @param ts unix-seconds
+ */
+export function relTime(ts: number): string {
+  const now  = Date.now();
+  const diff = now - ts * 1000;
+  if (diff < 60_000)              return 'now';
+  if (diff < 3_600_000)           return `${Math.floor(diff / 60_000)}m`;
+  if (diff < 24 * 3_600_000)      return `${Math.floor(diff / 3_600_000)}h`;
+  if (diff < 7 * 24 * 3_600_000)  return `${Math.floor(diff / (24 * 3_600_000))}d`;
+  const d = new Date(ts * 1000);
+  return `${String(d.getHours()).padStart(2, '0')}:${String(d.getMinutes()).padStart(2, '0')}`;
+}
+
+/**
+ * Похоже на relTime, но принимает как unix-seconds, так и unix-ms.
+ * Используется в chat-list tiles (там timestamp бывает в ms от addedAt).
+ */
+export function formatWhen(ts: number): string {
+  // Heuristic: > 1e12 → уже в ms, иначе seconds.
+  const sec = ts > 1e12 ? Math.floor(ts / 1000) : ts;
+  return relTime(sec);
+}
+
+/** "HH:MM" — одна и та же локаль, без дня. */
+export function formatHM(ts: number): string {
+  const d = new Date(ts * 1000);
+  return `${String(d.getHours()).padStart(2, '0')}:${String(d.getMinutes()).padStart(2, '0')}`;
+}