feat: add about page, global stats counter, and blitz screen updates

- Create about page with game modes, technologies, and paliers
- Add stats API endpoint for global game counter
- Update home screen with emoji-based tier system (🌱-🚀)
- Rewrite BlitzScreen to match new puzzle-based win/lose phases
- Add simple-icons package for tech stack icons
- Update metadata with wikirush.xyz domain
- Fix em dashes to hyphens throughout codebase
- Update footer with privacy and about links

app/components/GameScreen.tsx

@@ -148,7 +148,7 @@ export function GameScreen({
           )}
         </div>
 
-        {/* Sidebar — desktop seulement */}
+        {/* Sidebar - desktop seulement */}
         <aside className="hidden md:flex w-36 lg:w-44 shrink-0 bg-[#1a1a1a] border-l border-[#2e2e2e] flex-col px-3 py-4 overflow-y-auto gap-3">
           <h4 className="text-[10px] font-bold uppercase tracking-wider text-[#888]">Joueurs</h4>
           <ul className="flex flex-col gap-2.5">