feat(web): add smooth page transitions and WASM loading states

- Implement navigation state tracking with optimistic UI updates
- Add loading spinner and error handling for WASM initialization
- Insert browser yield points during game initialization to prevent freezing
- Redesign leaderboard with tabbed navigation and mock data structure
- Add utility CSS classes for consistent page layouts

web/pages/index/+Layout.tsx

@@ -1,5 +1,3 @@
-import "../../layouts/tailwind.css";
-
 export default function GameLayout({ children }: { children: React.ReactNode }) {
   return (
     <div className="bg-black text-yellow-400 h-full flex flex-col overflow-hidden">