cli 1.0.54 keyboard input not working on macos - prompting for username in background

### Describe the bug

When starting `copilot` I'm finding the text input unresponsive, and presented partially over the TUI is the message `Username for 'https://github.com':`. Over time, this message appears multiple times.

The app also doesn't directly respond to Ctrl^C

This is on Macos Tahoe 26.4.1 in both Ghostty and iTerm2, installing `copilot` via brew

### Affected version

GitHub Copilot CLI 1.0.54

### Steps to reproduce the behavior

1. Go to empty folder in Ghostty/iTerm2
2. Start copilot
3. Input doesn't work

### Expected behavior

Should be able to type prompts into the copilot TUI

### Additional context

- Operating system: Macos Tahoe 26.4.1
- CPU architecture: M4 Pro
- Terminal emulator: Ghostty 1.3.1 Build 15212
- Shell: zsh 5.9

Start by reproducing the issue in an empty folder on macOS Tahoe using Ghostty or iTerm2, with the Homebrew-installed copilot CLI. Investigate why the background GitHub username prompt prevents TUI input and Ctrl-C; done means prompts accept keyboard input normally without repeated username prompts.

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