Add backend status timestamp endpoint

backend/internal/httpx/router.go

@@ -2,6 +2,7 @@ package httpx
 
 import (
 	"net/http"
+	"time"
 
 	"github.com/gin-gonic/gin"
 	"senlinai-agent/backend/internal/config"
@@ -33,6 +34,9 @@ func newRouter(cfg config.Config, tokenVerifier func(string) (uint, error), regi
 		c.JSON(http.StatusOK, gin.H{"status": "ok"})
 	})
 	api := router.Group("/api")
+	api.GET("/status", func(c *gin.Context) {
+		c.JSON(http.StatusOK, gin.H{"timestamp_ms": time.Now().UnixMilli()})
+	})
 	if tokenVerifier != nil {
 		api.Use(auth.RequireUser(tokenVerifier))
 	}