feat: multiball assets

lib/game/game_assets.dart

@@ -101,6 +101,14 @@ extension PinballGameAssetsX on PinballGame {
       images.load(components.Assets.images.googleWord.letter5.keyName),
       images.load(components.Assets.images.googleWord.letter6.keyName),
       images.load(components.Assets.images.backboard.display.keyName),
+      images.load(components.Assets.images.multiball.a.active.keyName),
+      images.load(components.Assets.images.multiball.a.inactive.keyName),
+      images.load(components.Assets.images.multiball.b.active.keyName),
+      images.load(components.Assets.images.multiball.b.inactive.keyName),
+      images.load(components.Assets.images.multiball.c.active.keyName),
+      images.load(components.Assets.images.multiball.c.inactive.keyName),
+      images.load(components.Assets.images.multiball.d.active.keyName),
+      images.load(components.Assets.images.multiball.d.inactive.keyName),
       images.load(dashTheme.leaderboardIcon.keyName),
       images.load(sparkyTheme.leaderboardIcon.keyName),
       images.load(androidTheme.leaderboardIcon.keyName),