### Summary The Usage dashboard's **Ask AI** feature fails if the selected model is a LiteLLM model name / model group such as `mylitellmmodel`.

In my setup, `mylitellmmodel` is a valid LiteLLM proxy model name that routes to GPT-4.1. It works for normal proxy requests, but the Usage AI chat feature fails with:

```text litellm.BadRequestError: GetLLMProvider Exception - list index out of range

original model: mylitellmmodel ```

### Expected behavior The Usage AI chat should accept the same model names shown in the LiteLLM UI dropdown, including proxy model aliases / model groups.

If `mylitellmmodel` is a valid configured LiteLLM model name in the proxy, the Usage AI feature should work with it.

### Actual behavior The Usage AI feature posts the selected model name to `/usage/ai/chat`, and the backend calls `litellm.acompletion(model=<selected_model>)` directly.

If the selected model is a proxy alias / model group like `mylitellmmodel`, LiteLLM tries to interpret it as a raw model/provider string instead of resolving it through the proxy router, and fails.

### Error ```text litellm.BadRequestError: GetLLMProvider Exception - list index out of range

original model: mylitellm…