feat: 골드부족 팝업 instance 추가

Gameton-06/Assets/Gameton/Scripts/UI/GoldPopup.cs

@@ -6,6 +6,8 @@ namespace TON
 {
     public class GoldPopup : UIBase
     {
+        public static GoldPopup Instance => UIManager.Singleton.GetUI<GoldPopup>(UIList.GoldPopup);
+
         private void OnEnable()
         {
             Invoke(nameof(HidePopup), 3f);