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/TabHeader.tsx

@@ -0,0 +1,59 @@
+/**
+ * TabHeader — общая шапка для всех tab-страниц (home/feed/notifications/wallet).
+ *
+ * Структура строго как в референсе Messages-экрана:
+ *   [avatar 32 → /settings]   [title]   [right slot]
+ *
+ * Без нижнего разделителя (divider=false) — тот же уровень, что и фон экрана.
+ *
+ * Right-slot по умолчанию — шестерёнка → /settings. Но экраны могут передать
+ * свой (например, refresh в wallet). Левый avatar — всегда клик-навигация в
+ * settings, как в референсе.
+ */
+import React from 'react';
+import { Pressable } from 'react-native';
+import { useRouter } from 'expo-router';
+import { useStore } from '@/lib/store';
+import { Avatar } from '@/components/Avatar';
+import { Header } from '@/components/Header';
+import { IconButton } from '@/components/IconButton';
+
+export interface TabHeaderProps {
+  title: string;
+  /** Right-slot. Если не передан — выставляется IconButton с settings-outline. */
+  right?: React.ReactNode;
+  /** Dot-color на profile-avatar'е (например, WS live/polling indicator). */
+  profileDotColor?: string;
+}
+
+export function TabHeader({ title, right, profileDotColor }: TabHeaderProps) {
+  const router   = useRouter();
+  const username = useStore(s => s.username);
+  const keyFile  = useStore(s => s.keyFile);
+
+  return (
+    <Header
+      title={title}
+      divider={false}
+      left={
+        <Pressable onPress={() => router.push('/(app)/settings' as never)} hitSlop={8}>
+          <Avatar
+            name={username ?? '?'}
+            address={keyFile?.pub_key}
+            size={32}
+            dotColor={profileDotColor}
+          />
+        </Pressable>
+      }
+      right={
+        right ?? (
+          <IconButton
+            icon="settings-outline"
+            size={36}
+            onPress={() => router.push('/(app)/settings' as never)}
+          />
+        )
+      }
+    />
+  );
+}