chore: scaffold Next.js + Prisma + Tailwind

Initialise le projet Karbé :
- Next.js 16 (App Router, TypeScript) + Tailwind CSS v4 + ESLint
- Prisma avec datasource PostgreSQL, schema minimal et client généré
  dans src/generated/prisma (postinstall: prisma generate)
- Page d'accueil placeholder (titre + mission)
- .env.example (DATABASE_URL, NEXTAUTH_SECRET)
- README avec instructions de setup

Co-Authored-By: Paperclip <noreply@paperclip.ing>

package.json

@@ -0,0 +1,30 @@
+{
+  "name": "karbe",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "dev": "next dev",
+    "build": "next build",
+    "start": "next start",
+    "lint": "eslint",
+    "postinstall": "prisma generate"
+  },
+  "dependencies": {
+    "@prisma/client": "^7.8.0",
+    "next": "16.2.6",
+    "react": "19.2.4",
+    "react-dom": "19.2.4"
+  },
+  "devDependencies": {
+    "@tailwindcss/postcss": "^4",
+    "@types/node": "^20",
+    "@types/react": "^19",
+    "@types/react-dom": "^19",
+    "dotenv": "^17.4.2",
+    "eslint": "^9",
+    "eslint-config-next": "16.2.6",
+    "prisma": "^7.8.0",
+    "tailwindcss": "^4",
+    "typescript": "^5"
+  }
+}