fix: disable backgrounds on mobile

lib/game/game_assets.dart

@@ -2,6 +2,7 @@ import 'package:flame/extensions.dart';
 import 'package:pinball/game/game.dart';
 import 'package:pinball_components/pinball_components.dart' as components;
 import 'package:pinball_theme/pinball_theme.dart' hide Assets;
+import 'package:platform_helper/platform_helper.dart';
 
 /// Add methods to help loading and caching game assets.
 extension PinballGameAssetsX on PinballGame {
@@ -12,7 +13,7 @@ extension PinballGameAssetsX on PinballGame {
     const androidTheme = AndroidTheme();
     const dinoTheme = DinoTheme();
 
-    return [
+    final gameAssets = [
       images.load(components.Assets.images.boardBackground.keyName),
       images.load(components.Assets.images.ball.flameEffect.keyName),
       images.load(components.Assets.images.signpost.inactive.keyName),
@@ -140,17 +141,21 @@ extension PinballGameAssetsX on PinballGame {
       images.load(components.Assets.images.skillShot.lit.keyName),
       images.load(components.Assets.images.skillShot.dimmed.keyName),
       images.load(androidTheme.leaderboardIcon.keyName),
-      images.load(androidTheme.background.keyName),
       images.load(androidTheme.ball.keyName),
       images.load(dashTheme.leaderboardIcon.keyName),
-      images.load(dashTheme.background.keyName),
       images.load(dashTheme.ball.keyName),
       images.load(dinoTheme.leaderboardIcon.keyName),
-      images.load(dinoTheme.background.keyName),
       images.load(dinoTheme.ball.keyName),
       images.load(sparkyTheme.leaderboardIcon.keyName),
-      images.load(sparkyTheme.background.keyName),
       images.load(sparkyTheme.ball.keyName),
     ];
+
+    return (PlatformHelper().isMobile) ? gameAssets : gameAssets
+      ..addAll([
+        images.load(androidTheme.background.keyName),
+        images.load(dashTheme.background.keyName),
+        images.load(dinoTheme.background.keyName),
+        images.load(sparkyTheme.background.keyName),
+      ]);
   }
 }

lib/game/pinball_game.dart

@@ -14,6 +14,7 @@ import 'package:pinball/select_character/select_character.dart';
 import 'package:pinball_audio/pinball_audio.dart';
 import 'package:pinball_components/pinball_components.dart';
 import 'package:pinball_flame/pinball_flame.dart';
+import 'package:platform_helper/platform_helper.dart';
 
 class PinballGame extends PinballForge2DGame
     with HasKeyboardHandlerComponents, MultiTouchTapDetector, HasTappables {
@@ -101,7 +102,7 @@ class PinballGame extends PinballForge2DGame
                 children: [
                   ZCanvasComponent(
                     children: [
-                      ArcadeBackground(),
+                      if (!PlatformHelper().isMobile) ArcadeBackground(),
                       BoardBackgroundSpriteComponent(),
                       Boundaries(),
                       Backbox(