feat(aiot): 告警三表结构升级 + 腾讯云COS对象存储集成

1. 新增三表结构: alarm_event(主表), alarm_event_ext(算法扩展), alarm_llm_analysis(大模型分析)
2. 新增 AlarmEventService 服务，支持 MQTT/HTTP 双路创建告警
3. MQTT handler 双写新旧表，平滑过渡
4. 重写 yudao_aiot_alarm 路由，对接新告警服务
5. 集成腾讯云 COS 对象存储：上传、预签名URL、STS临时凭证
6. 新增 storage 路由：upload/presign/upload-url/sts 四个接口
7. COS 未启用时自动降级本地 uploads/ 目录存储
8. 新增数据迁移脚本 migrate_to_alarm_event.py
9. 删除根目录 main.py（非项目入口）

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/routers/__init__.py

@@ -8,10 +8,12 @@ from app.routers.yudao_auth import router as yudao_auth_router
 from app.routers.yudao_alert import router as yudao_alert_router
 from app.routers.yudao_aiot_alarm import router as yudao_aiot_alarm_router
 from app.routers.yudao_aiot_edge import router as yudao_aiot_edge_router
+from app.routers.yudao_aiot_storage import router as yudao_aiot_storage_router
 
 __all__ = [
     "yudao_auth_router",
     "yudao_alert_router",
     "yudao_aiot_alarm_router",
     "yudao_aiot_edge_router",
+    "yudao_aiot_storage_router",
 ]