Random text in in put field

### Describe the bug

Mac iterm2 text keeps getting randomly added to the input field making it hard to see what I'm actually trying to prompt. If i resize the window it appears to fix it, so it must be some kind of rendering bug.

### Affected version

v1.0.68

### Steps to reproduce the behavior

Open copilot, use it for a bit, it starts happening constantly.

### Expected behavior

Clean input field to type in

### Additional context

未指定原始檔案或測試。首先在 macOS iTerm2 中使用 Copilot CLI v1.0.68 重現問題，然後追蹤 CLI 輸入呈現的進入點；當使用期間或調整視窗大小後，文字不再隨機出現在輸入欄位中時，即表示完成。

由索引模型根據 Issue 內容生成。