feat(sprint1-step5): migration Tailwind v4 + Zustand — suppression WildCoinContext

- Install tailwindcss @tailwindcss/vite zustand
- useGameStore.ts : Zustand store wrappant economy.ts (tick, click, buy, prestige, buyNode, loadFromServer)
- GameTick.tsx : composant timer 1s
- GeneratorShop.tsx : boutique générateurs Tailwind (remplace Amelioration.jsx)
- EvolutionTree, PrestigePanel, MilestoneBar : rewrite Zustand + Tailwind
- Hud.jsx : rewrite Zustand + Tailwind (suppression Hud.scss)
- BoutiqueCard, Achievements : migrés vers Zustand
- Supprimé : WildCoin/ (4 fichiers), timer/Timer.jsx, useEconomy.ts, Hud.scss
- WildCoinProvider retiré de main.jsx

Frontend/package.json

@@ -11,12 +11,15 @@
     "test": "vitest run"
   },
   "dependencies": {
+    "@tailwindcss/vite": "^4.2.2",
     "react": "^18.2.0",
     "react-dom": "^18.2.0",
     "react-helmet": "^6.1.0",
     "react-lottie-player": "^1.5.5",
     "react-router-dom": "^6.19.0",
-    "sass": "^1.69.5"
+    "sass": "^1.69.5",
+    "tailwindcss": "^4.2.2",
+    "zustand": "^5.0.12"
   },
   "devDependencies": {
     "@types/react": "^18.3.28",