Claude Opus 4.6 (high) returns "model not supported" error after being told to wait for quota reset on GitHub Copilot Pro+

**Description**
After being prompted by the CLI to wait until a specific time before using Claude Opus 4.6 (high)
due to quota limits, I waited as instructed. Upon retrying, I now receive the following error:

Execution failed: CAPIError: 400 The requested model is not supported.
(Request ID: 49DD:6BE68:13F49D2:16EC696:69E6DD3C)

**Actual Behavior**
Error: CAPIError: 400 The requested model is not supported

**Environment**
- Plan: GitHub Copilot Pro+
- CLI Version: GitHub Copilot CLI 1.0.32
- OS: Windows

**Notes**
The error message is misleading -- it says "model not supported" rather than a quota or
availability issue, making it hard to diagnose.

### Affected version

GitHub Copilot CLI 1.0.32 onwards

### Steps to reproduce the behavior

**Steps to Reproduce**
1. Select Claude Opus 4.6 (high) via `/model` in Copilot CLI
2. Hit quota limit -- CLI prompts to wait until a specific time
3. Wait until the indicated time has passed
4. Try again -- error occurs

### Expected behavior

**Expected Behavior**
The model should be accessible after the quota reset window.

### Additional context

_No response_

Start with the `/model` flow in GitHub Copilot CLI 1.0.32 and reproduce the failure after the indicated quota reset on Windows. Trace the request for Claude Opus 4.6 (high) and compare the reported response with the quota or availability state. Done means the model works after reset or the error clearly identifies the actual limitation.

Escrita pelo modelo de indexação a partir do texto da issue.