"Copied to clipboard" notification is misleading when selecting text without Shift key

### Describe the bug

Environment:

• OS: macOS 26.5.2 (Build 25F84)
• Terminal: Ghostty 1.3.1
• Copilot CLI version: 1.0.68

When I select text with mouse, I get message "Copied to clipboard" however, when right click to pate, it states again "Copied to clipboard", the 2nd right click pastes instead of the first.

Workaround: Use Shift + select to copy text reliably.

### Affected version

GitHub Copilot CLI 1.0.68.

### Steps to reproduce the behavior

1. Mark text with mouse
2. Right-click

### Expected behavior

Text is pasted

### Additional context

_No response_

在 macOS 26.5.2 上使用 Ghostty 1.3.1，通过 GitHub Copilot CLI 1.0.68 重现该行为：使用鼠标选择文本，然后右键单击一次。跟踪从该交互开始的选择和剪贴板处理；完成标准是第一次右键单击会粘贴所选文本，而不是再次显示 "Copied to clipboard" 通知。

由索引模型根据 Issue 内容生成。