feat: scaffold frontend React 18 + Vite 5 + TypeScript

Mise en place de la structure de base du frontend HomeHub : React 18,
Vite 5, TypeScript strict, React Router v6, Tailwind CSS et vite-plugin-pwa
installés. Composants placeholder Layout et HomePage pour que le build
compile sans erreur. Build de production vérifié (dist/ généré, 0 erreur TS).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/tsconfig.app.json

@@ -0,0 +1,17 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "useDefineForClassFields": true,
+    "lib": ["ES2020", "DOM", "DOM.Iterable"],
+    "module": "ESNext",
+    "skipLibCheck": true,
+    "moduleResolution": "bundler",
+    "allowImportingTsExtensions": true,
+    "isolatedModules": true,
+    "moduleDetection": "force",
+    "noEmit": true,
+    "jsx": "react-jsx",
+    "strict": true
+  },
+  "include": ["src"]
+}