Feature/auth ui yigit

📌 Description

This merge request completes tasks 9, 10 and 11 related to the authentication system and lobby integration.

The following features were implemented and tested:

• User registration (Register page)
• User login with JWT token
• Token storage in localStorage
• Automatic redirect to lobby after authentication
• Connection to the backend API
• Socket connection established after login
• Lobby page accessible after successful authentication

All flows were tested locally: Register → Login → Lobby → Socket connection.

🔗 Lien vers l'issue

N/A

✅ Type de changement

• Feature (nouvelle fonctionnalité)
• Fix (correction de bug)

🧪 Comment tester

1. Run backend server
2. Run frontend client
3. Create a new user using the Register page
4. Login using the created credentials
5. Verify that the user is redirected to the Lobby
6. Check that the socket connection is established

✔ Checklist

• Authentication working (register & login)
• Frontend connected to backend API
• Socket connection working
• Tasks 9, 10 and 11 completed