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/omron_device_provider.dart

@@ -50,11 +50,13 @@ class DeviceBindState {
 
 class DeviceBindNotifier extends Notifier<DeviceBindState> {
   StreamSubscription<bool>? _connSub;
+  late String? _sessionIdentity;
 
   @override
   DeviceBindState build() {
+    _sessionIdentity = ref.watch(userSessionIdentityProvider);
     ref.onDispose(() => _connSub?.cancel());
-    _loadBinding();
+    if (_sessionIdentity != null) _loadBinding(_sessionIdentity!);
     _listenConnection();
     return const DeviceBindState();
   }
@@ -70,17 +72,36 @@ class DeviceBindNotifier extends Notifier<DeviceBindState> {
     });
   }
 
-  Future<void> _loadBinding() async {
+  String _accountKey(String baseKey, [String? session]) =>
+      '$baseKey:${session ?? _sessionIdentity}';
+
+  Future<void> _loadBinding(String session) async {
     final db = ref.read(localDbProvider);
-    await _migrateLegacyBloodPressureDevice();
-    final raw = await db.read(_boundDevicesKey);
+    await _migrateLegacyBloodPressureDevice(session);
+    final raw = await db.read(_accountKey(_boundDevicesKey, session));
     final devices = _decodeDevices(raw);
+    if (_sessionIdentity != session) return;
     state = state.copyWith(devices: devices);
   }
 
-  Future<void> _migrateLegacyBloodPressureDevice() async {
+  Future<void> _migrateLegacyBloodPressureDevice(String session) async {
     final db = ref.read(localDbProvider);
-    final existing = await db.read(_boundDevicesKey);
+    final accountKey = _accountKey(_boundDevicesKey, session);
+    final existing = await db.read(accountKey);
+    final oldSharedDevices = await db.read(_boundDevicesKey);
+    if (existing == null && oldSharedDevices != null) {
+      await db.write(accountKey, oldSharedDevices);
+      await db.delete(_boundDevicesKey);
+      final oldFingerprints = await db.read(_readingFingerprintsKey);
+      if (oldFingerprints != null) {
+        await db.write(
+          _accountKey(_readingFingerprintsKey, session),
+          oldFingerprints,
+        );
+        await db.delete(_readingFingerprintsKey);
+      }
+      return;
+    }
     final legacyMac = await db.read(_legacyBpMacKey);
     if (existing != null || legacyMac == null || legacyMac.isEmpty) return;
 
@@ -91,7 +112,7 @@ class DeviceBindNotifier extends Notifier<DeviceBindState> {
       type: BleDeviceType.bloodPressure,
       serviceUuid: BleDeviceType.bloodPressure.serviceUuid,
     );
-    await db.write(_boundDevicesKey, jsonEncode([migrated.toJson()]));
+    await db.write(accountKey, jsonEncode([migrated.toJson()]));
     await db.delete(_legacyBpMacKey);
     await db.delete(_legacyBpNameKey);
     await db.delete(_legacyBpLastSyncKey);
@@ -117,7 +138,7 @@ class DeviceBindNotifier extends Notifier<DeviceBindState> {
   Future<void> _saveDevices(List<BoundBleDevice> devices) async {
     final db = ref.read(localDbProvider);
     await db.write(
-      _boundDevicesKey,
+      _accountKey(_boundDevicesKey),
       jsonEncode(devices.map((device) => device.toJson()).toList()),
     );
     state = state.copyWith(devices: devices);
@@ -188,7 +209,7 @@ class DeviceBindNotifier extends Notifier<DeviceBindState> {
 
   Future<Map<String, String>> _loadFingerprints() async {
     final db = ref.read(localDbProvider);
-    final raw = await db.read(_readingFingerprintsKey);
+    final raw = await db.read(_accountKey(_readingFingerprintsKey));
     if (raw == null || raw.isEmpty) return {};
     try {
       final decoded = jsonDecode(raw);
@@ -203,7 +224,19 @@ class DeviceBindNotifier extends Notifier<DeviceBindState> {
 
   Future<void> _saveFingerprints(Map<String, String> fingerprints) async {
     final db = ref.read(localDbProvider);
-    await db.write(_readingFingerprintsKey, jsonEncode(fingerprints));
+    await db.write(
+      _accountKey(_readingFingerprintsKey),
+      jsonEncode(fingerprints),
+    );
+  }
+
+  Future<void> clearCurrentAccountData() async {
+    final session = _sessionIdentity;
+    if (session == null) return;
+    final db = ref.read(localDbProvider);
+    await db.delete(_accountKey(_boundDevicesKey, session));
+    await db.delete(_accountKey(_readingFingerprintsKey, session));
+    state = const DeviceBindState();
   }
 
   Map<String, String> _pruneFingerprints(