Copilot CLI changes terminal title to "Windows PowerShell" when not launched in Windows Terminal

### Describe the bug

When launched in a terminal that is not in Windows Terminal, Copilot CLI first set the terminal title to "GitHub Copilot", but it always automatically becomes "Windows PowerShell" after a second or two

### Affected version

1.0.79-5

### Steps to reproduce the behavior

1. Open a terminal in a host that's not Windows terminal, like cmd in Windows native conhost or Git Bash in mintty
2. Launch Copilot CLI
3. Observe the title change

### Expected behavior

The title should stay "GitHub Copilot" and not change to "Windows PowerShell"

### Additional context

_No response_

Reproduce the issue with Copilot CLI 1.0.79-5 in cmd or Git Bash in mintty, rather than Windows Terminal, and observe the terminal title over several seconds. Trace the terminal-title handling from CLI startup; done means the title remains "GitHub Copilot" instead of changing to "Windows PowerShell".

Written by the indexing model from the issue text.