feat: add opacity to game hud

lib/game/view/widgets/game_hud.dart

@@ -68,7 +68,9 @@ class _ScoreViewDecoration extends StatelessWidget {
     const radius = BorderRadius.all(Radius.circular(12));
     const borderWidth = 5.0;
 
-    return DecoratedBox(
+    return Opacity(
+      opacity: 0.7,
+      child: DecoratedBox(
         decoration: BoxDecoration(
           borderRadius: radius,
           border: Border.all(
@@ -89,6 +91,7 @@ class _ScoreViewDecoration extends StatelessWidget {
             child: child,
           ),
         ),
+      ),
     );
   }
 }