### Check for existing issues

- [x] I have searched the existing issues and checked that my issue is not a duplicate.

### What happened?

litellm xai-oauth login could success callback a auth.json , but router.py always reported error.

litellm.exceptions.BadRequestError: litellm.BadRequestError: You passed in model=grok-4.5. There are no healthy deployments for this modelNo fallback model group found for original model_group=grok-4.5

Exception: Unsupported provider - xai-oauth, ignoring and continuing...

it seems LlmProviders list missing the new defination . Thanks for function fixing.

### Steps to Reproduce

1. 2. 3.

### Relevant log output

```shell

```

### What part of LiteLLM is this about?

Proxy

### What LiteLLM version are you on ?

v1.92.0-rc.2

### Twitter / LinkedIn details

_No response_