When I click @copilot in a comment on a Pull Request, Copilot works, but it doesn't commit the changes to the PR

### Describe the bug

I use CodeRabbit to review pull requests, and based on a comment made by CodeRabbit or any user, I mention Copilot with @copilot to have it address the comment. It starts a work session, but doesn’t commit anything. The first screenshot shows the start of the session on the Pull Request screen, and the second shows the action that was performed in the Copilot instance that was launched based on my comment.

### Affected version

_No response_

### Steps to reproduce the behavior

_No response_

### Expected behavior

_No response_

### Additional context

_No response_

從 issue 中描述的 @copilot 工作流程開始：在 pull request 留言中提及 Copilot，並觀察因此產生的工作階段和 pull request 狀態。使用附加的螢幕截圖作為預期內容，接著判斷工作階段為何沒有產生 commit；完成後應重現該行為，並使要求的變更被 commit 到 pull request 中。

由索引模型根據 Issue 內容生成。