Clipboard copy broken while Copilot CLI is running (Windows)

## Bug Report

### Summary
While the GitHub Copilot CLI app is running, clipboard copy stops working entirely in that process. Selecting text and using right-click copy or Ctrl+C shows a 'copied to clipboard' confirmation, but nothing is actually written to the Windows clipboard — paste returns the previous clipboard content instead.

Clipboard functionality restores immediately upon exiting the CLI with \/exit\.

### Steps to Reproduce
1. Launch GitHub Copilot CLI on Windows
2. Select any text in the session output
3. Right-click → Copy (or Ctrl+C) — shows 'copied to clipboard'
4. Switch to any other app and paste
5. Previous clipboard content is pasted instead of the selected text

Also reproducible via:
\\\powershell
echo 'test' | clip
\\\
Run inside the CLI process — \Get-Clipboard\ reads it back fine within the same process, but the clipboard is not accessible from other applications.

### Expected Behavior
Selected text is copied to the Windows system clipboard and can be pasted in other apps.

### Actual Behavior
'Copied to clipboard' confirmation displays but clipboard is not updated. Previous clipboard content persists.

### Environment
- OS: Windows
- Copilot CLI version: 1.0.66
- RDP (Windows App) was connected at time of discovery but issue persists after disconnecting

### Workaround
Exit the CLI with \/exit\ — clipboard works again immediately in PowerShell.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

未指定文件、测试或入口点。首先，通过运行 CLI 和提供的 PowerShell 剪贴板命令在 Windows 上复现该故障，然后追踪 CLI 如何与系统剪贴板交互。当 CLI 仍在运行时，复制的 CLI 文本可供其他应用程序使用，且不会使文档中所述的变通方案发生回归，即视为完成。

由索引模型根据 Issue 内容生成。