feat: main.go 接入 ConversationHandler 路由注册

backend/cmd/server/main.go

@@ -140,6 +140,10 @@ func main() {
 	authHandler := api.NewAuthHandler(authService, tokenMgr)
 	authHandler.RegisterRoutes(apiGroup)
 
+	// Conversation REST 端点
+	convHandler := api.NewConversationHandler(sessionMgr, tokenMgr)
+	convHandler.RegisterRoutes(apiGroup)
+
 	// WebSocket
 	r.GET("/ws", ws.ServeWS(sessionMgr, orch, cfg))