UTKInput Validation 기능 추가

Assets/Sample/UIToolkit/UTKPropertyListWindowSample.cs

@@ -96,6 +96,10 @@ namespace UVC.Sample.UIToolkit
             _propertyWindow.OnPropertyButtonClicked += (id, actionName) =>
             {
                 Debug.Log($"Button Clicked: {id} - Action: {actionName}");
+                if(id == "string_with_btn" && actionName == "string_action")
+                {
+                    _propertyWindow.SetPropertyValue("string_with_btn", "Button clicked!");
+                }
             };
 
             // 샘플 데이터 생성