[IDE] aiChatAvailableModels query from LS returns an error when self-hosted models are configured with offline license
## Description
The LSP's `aiChatAvailableModels` GraphQL query returns `Internal server error` on SM instances with an offline cloud license and self-hosted models configured. This **does not** affect functionality of agentic chat– in fact, it is expected as this query fetches available models for user-level model selection, which is currently not supported with self-hosted models \[[ref](https://gitlab.com/gitlab-org/gitlab/-/work_items/594381#note_3239316074)\].
{width="338" height="137"}
However, this shouldn’t surface as an error that can confuse users.
## Steps to Reproduce
**Prerequisites**:
- Create a project in the testing instance and clone locally.
- Ensure you have the GitLab Workflow Extension installed on VSCode.
- Setup GitLab authentication with your instance:
- Open the command palette (Cmd+Shift+P) \> type in `GitLab: Authenticate`
- `Manually enter instance URL` \> Enter your instance URL
- Select `Create a token`
- Ensure the account you just authenticated with is selected.
**Steps**:
- Open the cloned project and open agentic chat in the Activity Bar.
- Observe error message.
## Acceptance Criteria
- [ ] Update resolver to gracefully handle offline license with self-hosted models case.
issue