feat(mobile): upload queue ui and continuous capture page

Task 9 (P3 plan): queue tab replaces the stub, continuous capture page
enqueues per shot, album detail gains an upload FAB, and the upload
engine lifecycle is now bound to the login session.

- Engine scope: session account drives UploadEngine start/stop; wired
  from app boot, login success, logout, and 401 eviction. Tasks stay in
  the store across logout (accountId hard isolation).
- Queue tab: album x state x time filter bar, task rows with thumbnail,
  state chip, localized error copy, attempt count, per-row progress via
  a broadcast progress hub, state-dependent actions (re-pick retry,
  retryNow, cancel, delete), batch retry bar, 200ms-debounced live
  refresh from drift table updates.
- Capture page: camera preview via injected CaptureSource, one enqueue
  per shutter press, persistent album/category/badges overlay with a
  switch-only-affects-new-shots hint, gallery multi-pick, exit confirm
  while uploads are pending, permission-denied and init-failure views.
- POST_NOTIFICATIONS runtime permission via a small MethodChannel
  (photolive/permissions) + PermissionPlugin.kt: single runtime
  permission need, avoids permission_handler dependency; requested once
  on first enqueue, silent degradation when denied or unavailable.
- Album detail FAB: capture-and-upload / pick-from-gallery sheet.
- l10n: ~50 new keys in zh/en arbs; tests: +45 (filter matrix, engine
  scope lifecycle, permission gate, queue tab, capture page, FAB entry);
  existing page tests updated to inject session/task-store fakes.

Co-Authored-By: Claude Code <noreply@anthropic.com>

apps/mobile/lib/features/uploads/task_store.dart

@@ -237,6 +237,11 @@ class TaskStore {
   /// 关闭底层数据库（App 退出/测试 tearDown）。
   Future<void> close() => _db.close();
 
+  /// 表写通知流（drift 对 insert/update/delete 自动发事件；队列 UI 的
+  /// 节流刷新挂接点——引擎/准备器每次落库都会触发）。
+  Stream<void> get changes =>
+      _db.tableUpdates().map<void>((Set<TableUpdate> _) {});
+
   /// 时间戳统一 UTC 落库（datetime 为 ISO-8601 文本存储：UTC 值以 `Z`
   /// 结尾、本地值带 `+hh:mm` 后缀，混存会让 SQL 文本比较错位一个时区
   /// 偏移——全部归一 UTC 后字典序即时间序）。