feat(client): 实时授权状态与会话失效处理

- 心跳读取 /auth/ping 回带的授权概况，直接刷新横幅/状态栏/只读门禁，省去单独轮询 /license/info
- 账号被停用/删除（401 USER_DISABLED）即强制重新登录
- 令牌持久化经串行队列 + 会话代号守卫，杜绝续期写入与登出交叉把失效 token 写回
- 写操作门禁（write_guard）+ 授权文案（license_copy）按 grace/readonly/locked 分阶段降级

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/test/stock_in_screen_test.dart

@@ -5,10 +5,24 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:go_router/go_router.dart';
 import 'package:jiu_client/core/models/page_result.dart';
+import 'package:jiu_client/models/license.dart';
 import 'package:jiu_client/models/stock_in.dart';
+import 'package:jiu_client/providers/license_provider.dart';
 import 'package:jiu_client/providers/stock_in_provider.dart';
 import 'package:jiu_client/screens/stock_in/stock_in_list_screen.dart';
 
+/// WriteGuard 内层会 watch licenseProvider；覆写成同步 normal 授权，避免真实网络请求。
+class _FakeLicenseNotifier extends LicenseNotifier {
+  @override
+  Future<LicenseInfo?> build() async => const LicenseInfo(
+        id: 1,
+        type: 'annual',
+        isActive: true,
+        maxDevices: 3,
+        phase: 'normal',
+      );
+}
+
 // ---------------------------------------------------------------------------
 // Fake notifier
 // ---------------------------------------------------------------------------
@@ -102,6 +116,7 @@ Widget _buildApp(AsyncValue<PageResult<StockInOrder>> state) {
 
   return ProviderScope(
     overrides: [
+      licenseProvider.overrideWith(() => _FakeLicenseNotifier()),
       stockInListProvider.overrideWith(() => _FakeStockInNotifier(state)),
     ],
     child: MaterialApp.router(routerConfig: router),
@@ -125,6 +140,7 @@ Widget _buildLoadingApp() {
 
   return ProviderScope(
     overrides: [
+      licenseProvider.overrideWith(() => _FakeLicenseNotifier()),
       stockInListProvider.overrideWith(() => _FakeLoadingStockInNotifier()),
     ],
     child: MaterialApp.router(routerConfig: router),