Implement JWT logout endpoint with token revocation and update unit tests

[MarkCh20]

…estsThis PR implements secure logout functionality with full token revocation support.

Key changes:

1. Added AuthController.logout() endpoint.
2. Updated AuthServiceImpl to store revoked tokens in the database.
3. Introduced RevokedToken entity and repository, with Flyway migration.
4. Unit tests updated for:
   • Revoked tokens
   • Malformed and invalid tokens
   • Refresh token strict stubbing
5. Logout flow verified in Postman: revoked tokens cannot be reused.

This ensures improved session management and security by invalidating JWT tokens upon logout.