add Metric

internal/services/api/handler_metrics.go

@@ -0,0 +1,13 @@
+package api
+
+import (
+	"github.com/gin-gonic/gin"
+	"net/http"
+	"thuanle.me/ip-info/internal/services/db_updater"
+)
+
+func HandleMetrics(c *gin.Context) {
+	c.JSON(http.StatusOK, gin.H{
+		"updated_at": db_updater.DbUpdatedAt.UnixMilli(),
+	})
+}