### Check for existing issues

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

### What happened?

The **Models + Endpoints** list in the UI is completely blank for an `internal_user` who logs in via SSO, when that user's model access is granted **only through model access groups** assigned to their team (or org). The **AI Hub** is also blank for the same reason. This is related to [#17475](https://github.com/BerriAI/litellm/issues/17475) though I'm not sure it's completely identical.

The root cause is a two-part gap in `get_available_models_for_user` (`litellm/proxy/utils.py`):

1. **The UI session token carries empty `team_models`.** When an SSO `internal_user` logs in, the minted `UserAPIKeyAuth` session token has `models = []` and `team_models = []` because the session is not scoped to a specific team API key. No team context (and therefore no team model access groups) is attached to the token.

2. **`get_available_models_for_user` never looks up the user's actual teams.** The function reads `team_models` directly from `user_api_key_dict.team_models`, which is always `[]` for a UI session token. It only fetches real team data when an…