feat: 文件存储安全加固 + 认证增强 + 媒体URL保护 + provider 重构

## 后端安全加固
- 新增 UserUploadPathResolver: 用户上传文件路径安全解析, 防目录穿越
- LocalReportFileStorage: 文件存储路径安全加固
- local_account_file_cleanup: 账号删除时文件清理逻辑增强
- AuthService: 认证逻辑增强
- file_endpoints / report_endpoints: 文件访问接口安全加固
- ai_chat_endpoints / doctor_endpoints: 接口安全调整
- Program.cs: 服务注册调整

## 前端认证与媒体
- 新增 authenticated_network_image.dart: 带认证的图片加载组件
- auth_provider: 认证状态管理大幅增强(+173)
- api_client: 网络客户端增强(+124)
- chat_provider: 聊天 provider 重构(+76)
- omron_device_provider: 蓝牙设备 provider 增强(+53)
- sse_handler: SSE 处理增强(+35)
- consultation_provider / data_providers / conversation_history_provider: 调整

## 页面调整
- remaining_pages: 健康档案/饮食记录等页面增强(+115)
- home_page / chat_messages_view: 主页微调
- doctor 端多页微调(consultations/dashboard/followups/patient_detail/profile/report_detail/reports)
- report_pages / settings_pages / notification_prefs_page: 微调
- device_scan_page / diet_capture_page / admin_home_page: 微调

## 测试
- 新增 file_path_security_tests: 文件路径安全测试
- 新增 protected_media_url_test: 媒体URL保护测试
- 新增 user_session_identity_test: 用户会话身份测试
- account_deletion_tests / application_service_tests / auth_tests: 更新

health_app/lib/providers/data_providers.dart

@@ -44,6 +44,7 @@ final inAppNotificationServiceProvider = Provider<InAppNotificationService>((
 });
 
 final notificationUnreadCountProvider = FutureProvider<int>((ref) async {
+  ref.watch(userSessionIdentityProvider);
   final history = await ref
       .watch(inAppNotificationServiceProvider)
       .getHistory();
@@ -52,6 +53,7 @@ final notificationUnreadCountProvider = FutureProvider<int>((ref) async {
 
 /// 最新健康数据 Provider
 final latestHealthProvider = FutureProvider<Map<String, dynamic>>((ref) async {
+  ref.watch(userSessionIdentityProvider);
   final service = ref.watch(healthServiceProvider);
   return service.getLatest();
 });
@@ -60,6 +62,7 @@ final latestHealthProvider = FutureProvider<Map<String, dynamic>>((ref) async {
 final medicationListProvider = FutureProvider<List<Map<String, dynamic>>>((
   ref,
 ) async {
+  ref.watch(userSessionIdentityProvider);
   final service = ref.watch(medicationServiceProvider);
   return service.getList();
 });
@@ -67,24 +70,28 @@ final medicationListProvider = FutureProvider<List<Map<String, dynamic>>>((
 final exercisePlansProvider = FutureProvider<List<Map<String, dynamic>>>((
   ref,
 ) async {
+  ref.watch(userSessionIdentityProvider);
   return ref.watch(exerciseServiceProvider).getPlans();
 });
 
 final followUpListProvider = FutureProvider<List<Map<String, dynamic>>>((
   ref,
 ) async {
+  ref.watch(userSessionIdentityProvider);
   return ref.watch(followUpServiceProvider).getList();
 });
 
 final dietRecordsProvider = FutureProvider<List<Map<String, dynamic>>>((
   ref,
 ) async {
+  ref.watch(userSessionIdentityProvider);
   return ref.watch(dietServiceProvider).getRecords();
 });
 
 final medicationReminderProvider = FutureProvider<List<Map<String, dynamic>>>((
   ref,
 ) async {
+  ref.watch(userSessionIdentityProvider);
   final service = ref.watch(medicationServiceProvider);
   return service.getReminders();
 });
@@ -92,6 +99,7 @@ final medicationReminderProvider = FutureProvider<List<Map<String, dynamic>>>((
 /// 医生列表 Provider
 final doctorListProvider =
     FutureProvider.autoDispose<List<Map<String, dynamic>>>((ref) async {
+      ref.watch(userSessionIdentityProvider);
       final service = ref.watch(consultationServiceProvider);
       return service.getDoctors().timeout(const Duration(seconds: 8));
     });
@@ -100,6 +108,7 @@ final doctorListProvider =
 final currentExercisePlanProvider = FutureProvider<Map<String, dynamic>?>((
   ref,
 ) async {
+  ref.watch(userSessionIdentityProvider);
   final service = ref.watch(exerciseServiceProvider);
   return service.getCurrentPlan().timeout(const Duration(seconds: 8));
 });