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/lib/auth.ts

@@ -0,0 +1,72 @@
+import { NextAuthOptions } from "next-auth"
+import CredentialsProvider from "next-auth/providers/credentials"
+import { usersService } from "@/services/users"
+
+export const authOptions: NextAuthOptions = {
+  providers: [
+    CredentialsProvider({
+      name: "credentials",
+      credentials: {
+        email: { label: "Email", type: "email" },
+        password: { label: "Password", type: "password" }
+      },
+      async authorize(credentials) {
+        if (!credentials?.email || !credentials?.password) {
+          return null
+        }
+
+        try {
+          // Chercher l'utilisateur dans la base de données
+          const user = await usersService.getUserByEmail(credentials.email)
+          
+          if (!user) {
+            return null
+          }
+
+          // Vérifier le mot de passe
+          const isValidPassword = await usersService.verifyPassword(
+            credentials.password,
+            user.password
+          )
+
+          if (!isValidPassword) {
+            return null
+          }
+
+          return {
+            id: user.id,
+            email: user.email,
+            name: user.name || `${user.firstName || ''} ${user.lastName || ''}`.trim() || user.email,
+            firstName: user.firstName || undefined,
+            lastName: user.lastName || undefined,
+            avatar: user.avatar || undefined,
+            role: user.role,
+          }
+        } catch (error) {
+          console.error('Auth error:', error)
+          return null
+        }
+      }
+    })
+  ],
+  pages: {
+    signIn: "/login",
+  },
+  session: {
+    strategy: "jwt",
+  },
+  callbacks: {
+    async jwt({ token, user }) {
+      if (user) {
+        token.id = user.id
+      }
+      return token
+    },
+    async session({ session, token }) {
+      if (token && session.user) {
+        session.user.id = token.id as string
+      }
+      return session
+    },
+  },
+}