BUG: /skills UI intercepts mouse selection, preventing text copy

### Describe the bug

## Summary
The `/skills` command opens an interactive UI where mouse drag selection is intercepted, so users cannot copy text with normal mouse selection.

## Expected behavior
Users should be able to select and copy skill output with the mouse (or have an explicit copy/export affordance in that UI).

## Actual behavior
Mouse selection is captured by the `/skills` UI. Copy works in regular CLI output, but not in the `/skills` screen.

## Why this is a problem
The UI makes it difficult to copy skill names/details for reuse, sharing, or documentation.

## Repro steps
1. Run Copilot CLI.
2. Execute `/skills`.
3. Try selecting text with the mouse.
4. Observe that selection/copy is not possible as in normal terminal output.

## Notes
- This appears specific to the interactive `/skills` UI, not standard output rendering.
- A plain-text `skills` output remains copyable.

### Affected version

_No response_

### Steps to reproduce the behavior

_No response_

### Expected behavior

_No response_

### Additional context

_No response_

首先在 Copilot CLI 中使用 `/skills` 重现问题，并比较其中的鼠标选择与正常的 CLI 输出。找到交互式 `/skills` UI 的入口点，并确定实现方式是恢复终端选择，还是添加明确的复制/导出功能；验证之后是否可以复制 skill 名称和详细信息。

由索引模型根据 Issue 内容生成。