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/app/api/auth/[...nextauth]/route.ts

@@ -0,0 +1,6 @@
+import NextAuth from "next-auth"
+import { authOptions } from "@/lib/auth"
+
+const handler = NextAuth(authOptions)
+
+export { handler as GET, handler as POST }

src/app/api/auth/register/route.ts

@@ -0,0 +1,59 @@
+import { NextRequest, NextResponse } from 'next/server'
+import { usersService } from '@/services/users'
+
+export async function POST(request: NextRequest) {
+  try {
+    const { email, name, firstName, lastName, password } = await request.json()
+
+    // Validation
+    if (!email || !password) {
+      return NextResponse.json(
+        { error: 'Email et mot de passe requis' },
+        { status: 400 }
+      )
+    }
+
+    if (password.length < 6) {
+      return NextResponse.json(
+        { error: 'Le mot de passe doit contenir au moins 6 caractères' },
+        { status: 400 }
+      )
+    }
+
+    // Vérifier si l'email existe déjà
+    const emailExists = await usersService.emailExists(email)
+    if (emailExists) {
+      return NextResponse.json(
+        { error: 'Un compte avec cet email existe déjà' },
+        { status: 400 }
+      )
+    }
+
+    // Créer l'utilisateur
+    const user = await usersService.createUser({
+      email,
+      name,
+      firstName,
+      lastName,
+      password,
+    })
+
+    return NextResponse.json({
+      message: 'Compte créé avec succès',
+      user: {
+        id: user.id,
+        email: user.email,
+        name: user.name,
+        firstName: user.firstName,
+        lastName: user.lastName,
+      }
+    })
+
+  } catch (error) {
+    console.error('Registration error:', error)
+    return NextResponse.json(
+      { error: 'Erreur lors de la création du compte' },
+      { status: 500 }
+    )
+  }
+}