Fix player name UI and persist name between menu scenes

Assets/Scripts/PlayerNameInput.cs

@@ -31,7 +31,7 @@ public class PlayerNameInput : MonoBehaviour
         // Keep / ensure background Image
         var img = nameGO.GetComponent<Image>();
         if (img == null) img = nameGO.AddComponent<Image>();
-        img.color = new Color(0.08f, 0.10f, 0.20f, 0.92f);
+        img.color = Color.white;
 
         // Build viewport > (Placeholder + Text) child hierarchy required by TMP_InputField
         var viewportRT = MakeChild("Text Area", rt);