feat: AI 意图路由/草稿存储 + Prompts 模块化 + UI 视觉统一 + AI 同意门 + 资源更新

后端:
- 新增 ai_intent_router 意图路由
- 新增 AiEntryDraft 草稿存储 + EF 迁移
- 新增 Prompts 模块化（global/modules/rag/router）
- AI Agent handlers 扩展

前端:
- 新增 AI 同意门 (ai_consent_gate/provider/details_page)
- HealthMetricVisuals 视觉统一
- 设备扫描/管理页面优化
- agent 插图替换 + 趋势指标图标

配置:
- DeepSeek 模型改 deepseek-v4-flash
- .gitignore 加 artifacts/audit
- build.gradle.kts 签名配置调整

health_app/lib/pages/device/device_management_page.dart

@@ -162,10 +162,13 @@ class _DeviceManagementPageState extends ConsumerState<DeviceManagementPage>
   Future<bool> _ensureBlePermissions() async {
     Map<Permission, PermissionStatus> statuses;
     try {
-      statuses = await [
-        Permission.bluetoothScan,
-        Permission.bluetoothConnect,
-      ].request();
+      final permissions = <Permission>[
+        if (Platform.isAndroid) Permission.bluetoothScan,
+        if (Platform.isAndroid) Permission.bluetoothConnect,
+        // Android 11 and below require location permission for BLE scans.
+        if (Platform.isAndroid) Permission.locationWhenInUse,
+      ];
+      statuses = await permissions.request();
     } catch (_) {
       if (mounted) {
         setState(() => _pageMessage = '无法读取蓝牙权限状态');