### Describe the bug If no auth providers are enabled, the user is presented with a blank page. We should be more informative here. <img width="690" height="414" alt="Image" src="https://github.com/user-attachments/assets/b44f0f7e-7b55-47d0-9bba-8f46d6e02c80" /> ### To reproduce Deploy with `AUTH_CREDENTIALS_LOGIN_ENABLED` set to `false` ### Sourcebot deployment information Sourcebot version (e.g. v3.0.1): 4.5.1 ### Additional information _No response_