feat: import Chinese-localized Buzz source snapshot

Signed-off-by: cls_宁波本机 <908705107@qq.com>

mobile/lib/features/channels/thread_follows/thread_follows_provider.dart

@@ -0,0 +1,83 @@
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+
+import '../../../shared/relay/relay.dart';
+import '../../../shared/theme/theme_provider.dart';
+import '../../../shared/read_state/read_state_time.dart';
+import 'thread_follows_storage.dart';
+
+class ThreadFollowsState {
+  final Set<String> followedRootIds;
+
+  const ThreadFollowsState({this.followedRootIds = const {}});
+
+  bool isFollowing(String rootId) => followedRootIds.contains(rootId);
+}
+
+/// Followed thread roots for the signed-in identity. Follows feed the unread
+/// pipeline (`shouldNotifyForEvent`'s `followedRootIds`), so replies in a
+/// followed thread badge the channel even without participation.
+class ThreadFollowsNotifier extends Notifier<ThreadFollowsState> {
+  List<ThreadFollowEntry> _entries = const [];
+  String? _pubkey;
+
+  @override
+  ThreadFollowsState build() {
+    final pubkey = ref.watch(myPubkeyProvider)?.trim().toLowerCase();
+    _pubkey = pubkey;
+    if (pubkey == null || pubkey.isEmpty) {
+      _entries = const [];
+      return const ThreadFollowsState();
+    }
+
+    try {
+      _entries = ThreadFollowsStorage(
+        ref.read(savedPrefsProvider),
+      ).read(pubkey);
+    } catch (_) {
+      _entries = const [];
+    }
+    return _stateFromEntries();
+  }
+
+  void followThread(String rootId) {
+    if (rootId.isEmpty || _entries.any((e) => e.rootId == rootId)) return;
+    _entries = capThreadFollowEntries([
+      ..._entries,
+      ThreadFollowEntry(rootId: rootId, followedAt: currentUnixSeconds()),
+    ]);
+    _persist();
+    state = _stateFromEntries();
+  }
+
+  void unfollowThread(String rootId) {
+    final next = [
+      for (final entry in _entries)
+        if (entry.rootId != rootId) entry,
+    ];
+    if (next.length == _entries.length) return;
+    _entries = next;
+    _persist();
+    state = _stateFromEntries();
+  }
+
+  void _persist() {
+    final pubkey = _pubkey;
+    if (pubkey == null || pubkey.isEmpty) return;
+    try {
+      ThreadFollowsStorage(
+        ref.read(savedPrefsProvider),
+      ).write(pubkey, _entries);
+    } catch (_) {
+      // In-memory state still works this session.
+    }
+  }
+
+  ThreadFollowsState _stateFromEntries() => ThreadFollowsState(
+    followedRootIds: Set.unmodifiable({for (final e in _entries) e.rootId}),
+  );
+}
+
+final threadFollowsProvider =
+    NotifierProvider<ThreadFollowsNotifier, ThreadFollowsState>(
+      ThreadFollowsNotifier.new,
+    );

mobile/lib/features/channels/thread_follows/thread_follows_storage.dart

@@ -0,0 +1,68 @@
+import 'dart:convert';
+
+import 'package:shared_preferences/shared_preferences.dart';
+
+/// Persistence for followed thread root IDs.
+///
+/// Mirrors the desktop store (`useThreadFollows.ts`): per-pubkey entries of
+/// `{rootId, followedAt}`, capped at the oldest-out limit. Desktop keeps this
+/// client-local (localStorage), so mobile does the same with
+/// SharedPreferences — following on one device intentionally does not sync.
+const threadFollowsMaxEntries = 500;
+
+String threadFollowsKey(String pubkey) => 'buzz-thread-follows.v1:$pubkey';
+
+class ThreadFollowEntry {
+  final String rootId;
+  final int followedAt;
+
+  const ThreadFollowEntry({required this.rootId, required this.followedAt});
+
+  Map<String, dynamic> toJson() => {'rootId': rootId, 'followedAt': followedAt};
+}
+
+class ThreadFollowsStorage {
+  final SharedPreferences _prefs;
+
+  ThreadFollowsStorage(this._prefs);
+
+  List<ThreadFollowEntry> read(String pubkey) {
+    final raw = _prefs.getString(threadFollowsKey(pubkey));
+    if (raw == null || raw.isEmpty) return const [];
+
+    try {
+      final parsed = jsonDecode(raw);
+      if (parsed is! List) return const [];
+      return [
+        for (final entry in parsed)
+          if (entry is Map &&
+              entry['rootId'] is String &&
+              entry['followedAt'] is int)
+            ThreadFollowEntry(
+              rootId: entry['rootId'] as String,
+              followedAt: entry['followedAt'] as int,
+            ),
+      ];
+    } catch (_) {
+      return const [];
+    }
+  }
+
+  void write(String pubkey, List<ThreadFollowEntry> entries) {
+    _prefs.setString(
+      threadFollowsKey(pubkey),
+      jsonEncode([for (final entry in entries) entry.toJson()]),
+    );
+  }
+}
+
+/// Cap entries at [threadFollowsMaxEntries], evicting the oldest follows
+/// first — same policy as desktop's `capEntries`.
+List<ThreadFollowEntry> capThreadFollowEntries(
+  List<ThreadFollowEntry> entries,
+) {
+  if (entries.length <= threadFollowsMaxEntries) return entries;
+  final sorted = [...entries]
+    ..sort((a, b) => a.followedAt.compareTo(b.followedAt));
+  return sorted.sublist(sorted.length - threadFollowsMaxEntries);
+}