feat(ws): 在线状态管理（Redis SET + TTL 心跳续期）

- app/ws/online_service.go: 上线/下线/心跳续期/批量查询在线状态
- 集成到 WebSocket handler: 连接时写入 Redis, 断线时清除
- client.go: 添加 DisconnectHandler 回调
- Redis 键: echo:user:online (SET) + echo:user:status:{uid} (TTL 60s)

Made-with: Cursor

backend/go-service/app/provider/provider.go

@@ -28,6 +28,7 @@ type App struct {
 	WSHandler             *wsApp.Handler                              // WebSocket 连接处理器
 	Hub                   *ws.Hub                                     // WebSocket Hub 连接管理
 	PubSub                *ws.PubSub                                  // Redis Pub/Sub 消息路由
+	OnlineService         *wsApp.OnlineService                        // 在线状态管理服务
 	ContactController     *contactController.ContactController        // 联系人控制器
 }
 
@@ -43,6 +44,7 @@ func NewApp(
 	wsHandler *wsApp.Handler,
 	hub *ws.Hub,
 	pubsub *ws.PubSub,
+	onlineService *wsApp.OnlineService,
 	contactCtrl *contactController.ContactController,
 ) *App {
 	return &App{
@@ -56,6 +58,7 @@ func NewApp(
 		WSHandler:             wsHandler,
 		Hub:                   hub,
 		PubSub:                pubsub,
+		OnlineService:         onlineService,
 		ContactController:     contactCtrl,
 	}
 }

backend/go-service/app/provider/wire_gen.go

@@ -47,11 +47,12 @@ func InitializeApp(cfg *config.Config) (*App, error) {
 	userManageController := controller2.NewUserManageController(userManageService)
 	hub := ws.ProvideHub()
 	pubSub := ws.ProvidePubSub(client, hub)
-	handler := ws.ProvideWSHandler(hub, pubSub, jwtConfig)
+	onlineService := ws.ProvideOnlineService(client, hub, pubSub)
+	handler := ws.ProvideWSHandler(hub, pubSub, jwtConfig, onlineService)
 	friendshipDAO := dao3.NewFriendshipDAO(gormDB)
 	friendGroupDAO := dao3.NewFriendGroupDAO(gormDB)
 	contactService := service3.NewContactService(friendshipDAO, friendGroupDAO, pubSub)
 	contactController := controller3.NewContactController(contactService)
-	app := NewApp(cfg, gormDB, client, authService, authController, adminAuthController, userManageController, handler, hub, pubSub, contactController)
+	app := NewApp(cfg, gormDB, client, authService, authController, adminAuthController, userManageController, handler, hub, pubSub, onlineService, contactController)
 	return app, nil
 }