Right-click paste in "Plan Ready for Review" prompt pastes into previous input instead

### Describe the bug

When in Plan mode, at the "Plan Ready for Review" prompt, pasting text via right-click into the "Suggest changes" input field does not work. The pasted content does not appear in the current input. Instead, after exiting Plan mode, the pasted content appears in the previous input field.

### Affected version

1.0.21

### Steps to reproduce the behavior

1. Start a session in Plan mode using Git Bash
2. Wait until the plan is generated and the "Plan Ready for Review" prompt appears
3. Copy some text to the clipboard
4. Right-click in the "Suggest changes" input field to paste (Git Bash pastes clipboard content on right-click by default)
5. Observe that nothing is pasted into the current input
6. Exit Plan mode
7. Observe that the pasted content now appears in the previous input field

### Expected behavior

Pasted text should be inserted into the currently focused "Suggest changes" input field at the "Plan Ready for Review" prompt.

### Additional context

OS: Windows 11
Terminal: Git Bash (right-click = paste)
Copilot CLI version: (1.0.21)

在 Windows 11 上使用 Git Bash 於 Plan mode 中重現此問題，並檢查 "Plan Ready for Review" 提示及其 "Suggest changes" 輸入框的實作。追蹤右鍵貼上如何在目前的輸入框與先前的輸入框之間路由。完成標準是：離開 Plan mode 後，貼上的文字會出現在目前取得焦點的輸入框中，而不會出現在先前的輸入框中。

由索引模型根據 Issue 內容生成。