Refactor Auth system: move tokens from url to cookies + add user roles

[MaryemWannes]

We need to improve the current auth system with a few changes:

1. Remove reading tokens from the URL and use httpOnly cookies instead.
2. Add user forms (profile data / onboarding data).
3. Add user roles support (admin, operator, etc.).
4. Connect authentication and roles properly with the database.

• Replace token-in-URL with secure cookies
• Add user form (basic user information)
• Implement roles structure (admin/user/operator...)
• Fetch user roles from DB instead of JWT only
• Update middleware to read token from cookies

Closes #48