Phase 2: Authentication

Work Package: Login and registration page.
- Create UI for landing page. (2 days) -> Minh
- Create UI for login/registration page. (2 days) -> Minh
- Backend integration (JWT authentication). (3 days) -> Stefan
- Implement role-based routing. (2 days) -> Minh
  - from landing page to log in page
  - from log in to home page
  - from new survey to create-edit-survey