* feat: prevent disabling last enabled authentication method
Adds validation to ensure at least one authentication method remains enabled.
This prevents users from being locked out of the system by disabling all
authentication options.
Changes:
- Add canDisableAuthMethod helper to validate auth method state
- Update admin UI to disable toggle when only one method is active
- Add noAuthMethodsAvailable check in auth-root component
- Filter disabled OAuth options in OAuthOptions component
* fix: type and license checks
