When files encoded in Windows 1252 are edited, Copilot changes the encoding to UTF-8.

### Describe the bug

Copilot doesn't respect the original file encoding; it makes edits and changes the file format to UTF-8. I haven't found a prompt to prevent this from happening.

What it does, after saving the wrong file, is try to revert the encoding using scripts.

### Affected version

GitHub Copilot CLI 1.0.56.

### Steps to reproduce the behavior

1) Create a Windows1252 file and save in repo;
2) Ask the copilot to make changes.

### Expected behavior

Copilot needs to respect file encoding

### Additional context

_No response_

Reproduce the issue in GitHub Copilot CLI 1.0.56 with a Windows 1252 file, then trace the edit and save path used when Copilot changes it. Confirm that edits preserve the original encoding and verify the behavior against the reported reproduction steps; no source file or test is named in the issue.

Written by the indexing model from the issue text.