Introduce background spawning with parallax effect (#86)

Co-authored-by: Michal Pikulski <michal.a.pikulski@gmail.com>
Reviewed-on: #86

Assets/Scripts/Minigames/BirdPooper/ScrollingEntity.cs

@@ -117,8 +117,12 @@ namespace Minigames.BirdPooper
         /// </summary>
         protected virtual void OnValidate()
         {
+            // Skip validation for prefab assets (only run on scene instances)
+            if (UnityEditor.PrefabUtility.IsPartOfPrefabAsset(this))
+                return;
+
             // Only run in editor, not during play mode
-            if (UnityEditor.EditorApplication.isPlayingOrWillChangePlaymode)
+            if (Application.isPlaying || !Application.isEditor)
                 return;
 
             EdgeAnchor anchor = GetComponent<EdgeAnchor>();