feat: add authentication support and user model

- Updated `env.example` to include NextAuth configuration for authentication.
- Added `next-auth` dependency to manage user sessions.
- Introduced `User` model in Prisma schema with fields for user details and password hashing.
- Integrated `AuthProvider` in layout for session management across the app.
- Enhanced `Header` component with `AuthButton` for user authentication controls.

src/middleware.ts

@@ -0,0 +1,33 @@
+import { withAuth } from "next-auth/middleware"
+
+export default withAuth(
+  function middleware() {
+    // Le middleware s'exécute seulement si l'utilisateur est authentifié
+    // grâce à withAuth
+  },
+  {
+    callbacks: {
+      authorized: ({ token }) => {
+        // Vérifier si l'utilisateur a un token valide
+        return !!token
+      },
+    },
+  }
+)
+
+export const config = {
+  matcher: [
+    /*
+     * Match all request paths except for the ones starting with:
+     * - api/auth (NextAuth routes)
+     * - login (login page)
+     * - register (registration page)
+     * - profile (profile page)
+     * - _next/static (static files)
+     * - _next/image (image optimization files)
+     * - favicon.ico (favicon file)
+     * - public files (images, etc.)
+     */
+    '/((?!api/auth|login|register|profile|_next/static|_next/image|favicon.ico|.*\\.(?:svg|png|jpg|jpeg|gif|webp)$).*)',
+  ],
+}