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/engine_scope.dart

@@ -0,0 +1,67 @@
+/// 引擎生命周期绑定（P3 计划 Task 6 关注点 1，Task 9 接线）。
+///
+/// 登录会话账号（SessionStore.account）→ [UploadEngine.start] 的 scope：
+/// - 账号在场（App 启动恢复会话 / 登录成功）→ start(accountId)——待传
+///   队列尽快恢复出队（A05）；
+/// - 账号离场（登出 / 401 驱逐）→ stop()——**任务行保留在库内**，账号
+///   切换安全由 TaskStore 的 accountId 硬隔离守护保障；
+/// - 会话变更通知点：登录页成功、设置页登出、App 壳 401 回调，均调
+///   [SessionAccountNotifier.refresh]。
+///
+/// [uploadEngineScopeProvider] 由 App 壳（PhotoLiveApp.build）watch 保持
+/// 常驻——离开登录态即 stop，绝不遗留旧账号的周期出队。
+library;
+
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../../core/api_client.dart';
+import 'providers.dart';
+import 'upload_engine.dart';
+
+/// 会话账号 Notifier：读 SessionStore；登录/登出/401 后 refresh()。
+class SessionAccountNotifier extends AsyncNotifier<String?> {
+  @override
+  Future<String?> build() async {
+    final session = await ref.watch(sessionStoreProvider).read();
+    return _normalize(session?.account);
+  }
+
+  /// 重读会话（登录成功/登出/401 驱逐后调用）。
+  Future<void> refresh() async {
+    final store = ref.read(sessionStoreProvider);
+    state = const AsyncLoading<String?>();
+    state = await AsyncValue.guard(() async {
+      final session = await store.read();
+      return _normalize(session?.account);
+    });
+  }
+
+  /// 空串归一为 null（未登录语义；引擎 scope 判空依据）。
+  static String? _normalize(String? account) =>
+      (account == null || account.isEmpty) ? null : account;
+}
+
+/// 会话账号 Provider（引擎 scope 与队列/连拍 UI 的 accountId 来源）。
+final sessionAccountProvider =
+    AsyncNotifierProvider<SessionAccountNotifier, String?>(
+  SessionAccountNotifier.new,
+);
+
+/// 引擎生命周期绑定：账号在场 → start；离场 → stop（任务保留库内）。
+///
+/// 返回当前 scope 账号（null=引擎停止）；仅被 App 壳 watch 时生效
+/// （Provider 惰性求值）。
+final uploadEngineScopeProvider = Provider<String?>((ref) {
+  final account = ref.watch(sessionAccountProvider).value;
+  final engine = ref.watch(uploadEngineProvider);
+  if (account != null) {
+    engine.start(account);
+  } else {
+    engine.stop();
+  }
+  ref.onDispose(engine.stop);
+  return account;
+});
+
+/// 供文档引用的类型锚点（[UploadEngine] 生命周期语义见 upload_engine.dart）。
+typedef EngineLifecycleDoc = UploadEngine;