CTRL+C is a bit too efficient - cancel current running command - not whole session

### Describe the bug

- stop prompting to use "copilot fg" when I accidentally exit copilot - it does not work. And please - try to find a
way to show "Are you sure you want to exit" when a ctrl+c is entered too many times - cancelling a command should not be
treated as an exit - please use CTRL+D for exit

### Affected version

GitHub Copilot CLI 1.0.43.

### Steps to reproduce the behavior

CTRL+C too many times

### Expected behavior

Just cancel the running command

Use CTRL+D for exit

Stop issuing prompt "copilot fg" to resume - it does nothing

### Additional context

_No response_

复现 GitHub Copilot CLI 1.0.43 中重复按下 CTRL+C 时的行为，并跟踪命令取消、会话退出和 "copilot fg" 提示符的处理。完成的标准是：CTRL+C 只取消正在运行的命令，重复按下时提供退出确认而不是立即退出，CTRL+D 可以退出，并移除误导性的恢复提示。

由索引模型根据 Issue 内容生成。