Cmd+S in VS Code editor review triggers Save As instead of accepting the change

### Describe the bug

When Copilot CLI opens an editor in VS Code for reviewing changes (e.g., during a rebase), pressing Cmd+S triggers a Save As dialog instead of accepting the edit and closing the editor. This breaks the review workflow and adds significant friction.

By comparison, other terminal coding agents handle the same flow correctly: Cmd+S accepts the change and closes the editor window immediately, making it dramatically faster to move through edits.

### Affected version

GitHub Copilot CLI 0.0.410-1

### Steps to reproduce the behavior

1. Run Copilot CLI in VS Code's integrated terminal
2. Perform an operation that opens an editor for review (e.g., a rebase with conflicts)
3. Make edits in the opened editor tab
4. Press Cmd+S to save/accept the change
5. Observe: a Save As dialog appears instead of accepting the edit

### Expected behavior

Cmd+S should accept the change and close the editor, similar to how other terminal coding agents handle this flow.

### Additional context

_No response_