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/models/ble_device.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_blue_plus/flutter_blue_plus.dart';
 
+import '../core/app_module_visuals.dart';
 import 'bp_reading.dart';
 
 enum BleDeviceType { bloodPressure, glucose, weightScale, pulseOximeter }
@@ -43,10 +44,10 @@ extension BleDeviceTypeX on BleDeviceType {
   };
 
   IconData get icon => switch (this) {
-    BleDeviceType.bloodPressure => Icons.speed_rounded,
-    BleDeviceType.glucose => Icons.water_drop_rounded,
+    BleDeviceType.bloodPressure => HealthMetricVisuals.bloodPressureIcon,
+    BleDeviceType.glucose => HealthMetricVisuals.glucoseIcon,
     BleDeviceType.weightScale => Icons.monitor_weight_outlined,
-    BleDeviceType.pulseOximeter => Icons.air_rounded,
+    BleDeviceType.pulseOximeter => HealthMetricVisuals.spo2Icon,
   };
 
   static BleDeviceType? fromCode(String? code) {