chore: update game assets loader

lib/game/game_assets.dart

@@ -9,7 +9,10 @@ extension PinballGameAssetsX on PinballGame {
     return [
       images.load(components.Assets.images.ball.ball.keyName),
       images.load(components.Assets.images.ball.flameEffect.keyName),
-      images.load(components.Assets.images.flutterSignPost.keyName),
+      images.load(components.Assets.images.signPost.inactive.keyName),
+      images.load(components.Assets.images.signPost.active1.keyName),
+      images.load(components.Assets.images.signPost.active2.keyName),
+      images.load(components.Assets.images.signPost.active3.keyName),
       images.load(components.Assets.images.flipper.left.keyName),
       images.load(components.Assets.images.flipper.right.keyName),
       images.load(components.Assets.images.baseboard.left.keyName),