feat: configurable traffic threshold and Feishu bot alerts

backend/internal/api/api.go

@@ -310,6 +310,10 @@ func (s *Server) RegisterRoutes(r *gin.Engine) {
 		admin.Use(requireRole("admin"))
 		// 主机环境体检与一键初始化（仅 admin）
 		admin.GET("/system/env", s.systemEnv)
+		admin.GET("/system/alerts", s.getAlertSettings)
+		admin.PUT("/system/alerts", s.saveAlertSettings)
+		admin.DELETE("/system/alerts", s.clearAlertSettings)
+		admin.POST("/system/alerts/test", s.testAlertSettings)
 		admin.POST("/system/fix", s.systemFix)
 		admin.GET("/system/tls", s.tlsStatus)
 		admin.GET("/system/identity", idp.Status)