JWT handling

[FloatG]

Description: As a developer, I want to implement JWT handling in the application to secure API endpoints and authenticate users.

Acceptance Criteria:

1. Implement JWT-based authentication for user login and registration.
2. Ensure that upon successful authentication, the server issues a JWT token containing user information.
3. JWT tokens should have a configurable expiration time and be refreshed automatically when nearing expiration.
4. Create middleware to secure API endpoints by validating JWT tokens.
5. Unauthorized access to protected API endpoints should return a proper error response.
6. Implement a mechanism for users to log out, which invalidates their JWT token.
7. Develop unit tests to ensure the correctness of JWT handling functionality.

Definition of Done:

• JWT-based authentication is implemented and tested for user login and registration.
• JWT tokens are issued upon successful authentication.
• JWT tokens have a configurable expiration time and auto-refresh functionality.
• Middleware is created and tested for securing API endpoints with JWT validation.
• Unauthorized access to protected API endpoints returns a proper error response.
• Logout functionality is implemented and tested.
• Unit tests for JWT handling are developed and pass successfully.
• Code is reviewed and approved.
• Documentation is updated to explain JWT handling.