Implement Token Blacklisting in JWTHandler

[dillonhuston]

Currently, the /logout route is a stub. We need to implement a mechanism to store revoked JWTs (e.g., in a TokenBlacklist database table or Redis) and check them in the get_current_user dependency to ensure full security.

[GregoryMonzon]

I will take this. I will make the changes in the 'contributing' branch.