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_

Start by reproducing the issue in Copilot CLI with `/skills`, comparing mouse selection there with normal CLI output. Locate the interactive `/skills` UI entry point and determine whether completion means restoring terminal selection or adding an explicit copy/export affordance; verify that skill names and details can be copied afterward.

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