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/package.json

@@ -0,0 +1,61 @@
+{
+  "name": "dchain-messenger",
+  "version": "1.0.0",
+  "main": "expo-router/entry",
+  "scripts": {
+    "start": "expo start",
+    "android": "expo start --android",
+    "ios": "expo start --ios",
+    "web": "expo start --web",
+    "lint": "eslint ."
+  },
+  "dependencies": {
+    "@expo/metro-runtime": "~6.1.2",
+    "@react-native-async-storage/async-storage": "2.2.0",
+    "@react-native-community/netinfo": "11.4.1",
+    "class-variance-authority": "^0.7.1",
+    "clsx": "^2.1.1",
+    "expo": "~54.0.0",
+    "expo-asset": "~12.0.12",
+    "expo-audio": "~1.1.1",
+    "expo-camera": "~17.0.10",
+    "expo-clipboard": "~8.0.8",
+    "expo-constants": "~18.0.13",
+    "expo-crypto": "~15.0.8",
+    "expo-document-picker": "~14.0.8",
+    "expo-file-system": "~19.0.21",
+    "expo-font": "~14.0.11",
+    "expo-image-manipulator": "~14.0.8",
+    "expo-image-picker": "~17.0.10",
+    "expo-linking": "~8.0.11",
+    "expo-notifications": "~0.32.16",
+    "expo-router": "~6.0.23",
+    "expo-secure-store": "~15.0.8",
+    "expo-sharing": "~14.0.8",
+    "expo-splash-screen": "~31.0.13",
+    "expo-status-bar": "~3.0.9",
+    "expo-video": "~3.0.16",
+    "expo-web-browser": "~15.0.10",
+    "nativewind": "^4.1.23",
+    "react": "19.1.0",
+    "react-dom": "19.1.0",
+    "react-native": "0.81.5",
+    "react-native-gesture-handler": "~2.28.0",
+    "react-native-reanimated": "~4.1.1",
+    "react-native-safe-area-context": "~5.6.0",
+    "react-native-screens": "~4.16.0",
+    "react-native-web": "^0.21.0",
+    "react-native-worklets": "0.5.1",
+    "tailwind-merge": "^2.6.0",
+    "tailwindcss": "^3.4.17",
+    "tweetnacl": "^1.0.3",
+    "tweetnacl-util": "^0.15.1",
+    "zustand": "^5.0.3"
+  },
+  "devDependencies": {
+    "@babel/core": "^7.25.2",
+    "@types/react": "~19.1.0",
+    "babel-preset-expo": "~54.0.10",
+    "typescript": "^5.3.3"
+  }
+}