Permission prompt incorrectly associates non-git directory with CLI session's git repo when adding safe directory

### Describe the bug

Bug: When editing a file in a directory that is not under git (e.g., C:\temp\copilot), the permission prompt "Yes, and don't ask again for file operations in this repo" incorrectly references the CLI session's current git repository (C:\git\jdev\src) instead of the file's actual directory. The safe-directory association should be based on the file being edited, not the CLI's CWD.

### Affected version

You're running **GitHub Copilot CLI 1.0.56**. Worth including in your bug report!

### Steps to reproduce the behavior

start copilot in a directory that is under git control. tell copilot to create a file in a directory that is not under git control. it will ask if it can edit the file and then ask if it should put the git-controlled directory in the directories list

### Expected behavior

I would expect it to ask if it can put the directory where I've asked it to edit the file in its safe directories list.

### Additional context

_No response_

通过在 git 控制的目录中启动 CLI，并要求它在类似 C:\temp\copilot 的无关目录中创建文件，来复现 prompt。跟踪 safe-directory 选择如何与被编辑的文件关联，并确认 prompt 指出的是该文件所在的目录，而不是 CLI 会话当前的 repository。

由索引模型根据 Issue 内容生成。