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/auth_provider.dart

@@ -1,3 +1,4 @@
+import 'dart:convert';
 import 'dart:developer';
 
 import 'package:flutter_riverpod/flutter_riverpod.dart';
@@ -53,11 +54,15 @@ final apiClientProvider = Provider<ApiClient>((ref) {
 });
 
 class AuthNotifier extends Notifier<AuthState> {
+  static const _cachedUserKey = 'session_user';
+
   @override
   AuthState build() {
     final removeListener = ref.read(authExpiredNotifierProvider).addListener(
       () {
+        ref.read(localDbProvider).delete(_cachedUserKey);
         state = const AuthState(isLoggedIn: false, isLoading: false);
+        _publishSessionIdentity(null);
       },
     );
     ref.onDispose(removeListener);
@@ -72,30 +77,51 @@ class AuthNotifier extends Notifier<AuthState> {
     if (refresh == null) {
       // 无 token：判定完成、未登录
       state = const AuthState(isLoggedIn: false, isLoading: false);
+      _publishSessionIdentity(null);
       return;
     }
 
     state = const AuthState(isLoading: true);
     try {
       final response = await Dio(
-        BaseOptions(baseUrl: baseUrl),
+        BaseOptions(
+          baseUrl: baseUrl,
+          connectTimeout: const Duration(seconds: 5),
+          receiveTimeout: const Duration(seconds: 8),
+        ),
       ).post('/api/auth/refresh', data: {'refreshToken': refresh});
-      final data = response.data['data'];
-      if (data != null) {
+      final body = response.data;
+      final data = body is Map ? body['data'] : null;
+      final code = body is Map ? body['code'] : null;
+      if (data is Map) {
         await db.write('access_token', data['accessToken']);
         await db.write('refresh_token', data['refreshToken']);
         final u = data['user'] as Map<String, dynamic>?;
-        state = AuthState(
-          isLoggedIn: true,
-          isLoading: false,
-          user: UserInfo(id: '', phone: '', role: u?['role'] ?? 'User'),
-        );
+        final cachedUser = await _readCachedUser();
+        final user = _userFromMap(u, fallback: cachedUser);
+        state = AuthState(isLoggedIn: true, isLoading: false, user: user);
+        _publishSessionIdentity(user);
+        await _cacheUser(user);
         _loadProfile();
-      } else {
+      } else if (code != null && code != 0) {
+        await _clearSessionStorage();
         state = const AuthState(isLoggedIn: false, isLoading: false);
+        _publishSessionIdentity(null);
+      } else {
+        await _restoreOfflineSession();
       }
-    } catch (_) {
-      state = const AuthState(isLoggedIn: false, isLoading: false);
+    } on DioException catch (error) {
+      if (error.response?.statusCode == 400 ||
+          error.response?.statusCode == 401) {
+        await _clearSessionStorage();
+        state = const AuthState(isLoggedIn: false, isLoading: false);
+        _publishSessionIdentity(null);
+      } else {
+        await _restoreOfflineSession();
+      }
+    } catch (error) {
+      log('[Auth] startup refresh: $error');
+      await _restoreOfflineSession();
     }
   }
 
@@ -120,6 +146,8 @@ class AuthNotifier extends Notifier<AuthState> {
             birthDate: user['birthDate']?.toString(),
           ),
         );
+        await _cacheUser(state.user!);
+        _publishSessionIdentity(state.user);
       }
     } catch (e) {
       log('[Auth] loadProfile: $e');
@@ -177,6 +205,8 @@ class AuthNotifier extends Notifier<AuthState> {
           role: user['role'] ?? 'User',
         ),
       );
+      await _cacheUser(state.user!);
+      _publishSessionIdentity(state.user);
       return null;
     } catch (e) {
       return '注册失败: $e';
@@ -207,6 +237,8 @@ class AuthNotifier extends Notifier<AuthState> {
           avatarUrl: user['avatarUrl'],
         ),
       );
+      await _cacheUser(state.user!);
+      _publishSessionIdentity(state.user);
       return null;
     } catch (e) {
       return '登录失败: $e';
@@ -245,6 +277,8 @@ class AuthNotifier extends Notifier<AuthState> {
           avatarUrl: user['avatarUrl'],
         ),
       );
+      await _cacheUser(state.user!);
+      _publishSessionIdentity(state.user);
       return null;
     } catch (_) {
       return 'Apple 登录失败，请稍后重试';
@@ -264,7 +298,108 @@ class AuthNotifier extends Notifier<AuthState> {
       }
     }
     await api.clearTokens();
+    await db.delete(_cachedUserKey);
     state = const AuthState(isLoggedIn: false, isLoading: false);
+    _publishSessionIdentity(null);
+  }
+
+  Future<void> _restoreOfflineSession() async {
+    final cached = await _readCachedUser() ?? await _userFromStoredToken();
+    if (cached == null) {
+      state = const AuthState(isLoggedIn: false, isLoading: false);
+      _publishSessionIdentity(null);
+      return;
+    }
+    state = AuthState(user: cached, isLoggedIn: true, isLoading: false);
+    _publishSessionIdentity(cached);
+  }
+
+  UserInfo _userFromMap(Map<String, dynamic>? value, {UserInfo? fallback}) {
+    return UserInfo(
+      id: value?['id']?.toString() ?? fallback?.id ?? '',
+      phone: value?['phone']?.toString() ?? fallback?.phone ?? '',
+      role: value?['role']?.toString() ?? fallback?.role ?? 'User',
+      name: value?['name']?.toString() ?? fallback?.name,
+      avatarUrl: value?['avatarUrl']?.toString() ?? fallback?.avatarUrl,
+      gender: value?['gender']?.toString() ?? fallback?.gender,
+      birthDate: value?['birthDate']?.toString() ?? fallback?.birthDate,
+    );
+  }
+
+  Future<void> _cacheUser(UserInfo user) {
+    return ref
+        .read(localDbProvider)
+        .write(
+          _cachedUserKey,
+          jsonEncode({
+            'id': user.id,
+            'phone': user.phone,
+            'role': user.role,
+            'name': user.name,
+            'avatarUrl': user.avatarUrl,
+            'gender': user.gender,
+            'birthDate': user.birthDate,
+          }),
+        );
+  }
+
+  Future<UserInfo?> _readCachedUser() async {
+    final raw = await ref.read(localDbProvider).read(_cachedUserKey);
+    if (raw == null || raw.isEmpty) return null;
+    try {
+      final decoded = jsonDecode(raw);
+      if (decoded is! Map) return null;
+      return _userFromMap(Map<String, dynamic>.from(decoded));
+    } catch (_) {
+      return null;
+    }
+  }
+
+  Future<UserInfo?> _userFromStoredToken() async {
+    final token = await ref.read(localDbProvider).read('access_token');
+    if (token == null) return null;
+    try {
+      final parts = token.split('.');
+      if (parts.length != 3) return null;
+      final payload = jsonDecode(
+        utf8.decode(base64Url.decode(base64Url.normalize(parts[1]))),
+      );
+      if (payload is! Map) return null;
+      final map = Map<String, dynamic>.from(payload);
+      String? claim(String shortName, String longName) =>
+          map[shortName]?.toString() ?? map[longName]?.toString();
+      return UserInfo(
+        id:
+            claim(
+              'sub',
+              'http://schemas.xmlsoap.org/ws/2005/05/identity/claims/nameidentifier',
+            ) ??
+            '',
+        phone:
+            claim(
+              'phone',
+              'http://schemas.xmlsoap.org/ws/2005/05/identity/claims/mobilephone',
+            ) ??
+            '',
+        role:
+            claim(
+              'role',
+              'http://schemas.microsoft.com/ws/2008/06/identity/claims/role',
+            ) ??
+            'User',
+      );
+    } catch (_) {
+      return null;
+    }
+  }
+
+  Future<void> _clearSessionStorage() async {
+    await ref.read(apiClientProvider).clearTokens();
+    await ref.read(localDbProvider).delete(_cachedUserKey);
+  }
+
+  void _publishSessionIdentity(UserInfo? user) {
+    ref.read(userSessionIdentityProvider.notifier).setUser(user);
   }
 }
 
@@ -272,3 +407,21 @@ class AuthNotifier extends Notifier<AuthState> {
 final userRoleProvider = Provider<String>((ref) {
   return ref.watch(authProvider).user?.role ?? 'User';
 });
+
+final userSessionIdentityProvider =
+    NotifierProvider<UserSessionIdentityNotifier, String?>(
+      UserSessionIdentityNotifier.new,
+    );
+
+class UserSessionIdentityNotifier extends Notifier<String?> {
+  @override
+  String? build() => null;
+
+  void setUser(UserInfo? user) {
+    if (user == null || user.id.isEmpty) {
+      state = null;
+      return;
+    }
+    state = user.id;
+  }
+}