[FR] Allow disabling registration

[Eidenz]

Would be nice to allow disabling registration with an environment variable for production

[WaveringAna]

The backend already closes registration after the first user is created with the admin token, do you want it to be closed entirely anyway?

[Eidenz]

Oh, so it's single user only? It's just that seeing the register page despite registration closed is a bit confusing. So it'd be frontend only, like hiding the register tab if we can't register more users.

[WaveringAna]

yeah its single user; im planning on changing the flow a bit to show the registration if theres no users then only showing login

[WaveringAna]

merged