Hardcoded colors in 1.0.61 break the light themed CLI

### Describe the bug

Hardcoded background color breaks the light CMD theme.

### Affected version

GitHub Copilot CLI 1.0.61.

### Steps to reproduce the behavior

1. Set the light theme in Windows / Terminal
2. Run Github Copilot
3. Look at the screen

### Expected behavior

Allow reusing colors from Terminal Preview as many users set up the theme there.
Or, check if the Windows color scheme is light or dark before applying colors.
Many users are switching to light themes when working outdoors on a sunny day as the text is much better visible in such conditions.

### Additional context

_No response_

Start by reproducing the issue in Windows Terminal with its light theme using GitHub Copilot CLI 1.0.61, then trace where CLI colors are initialized or applied. Done means the CLI no longer forces a dark background and respects the terminal or Windows light/dark color setting; verify the result in both light and dark themes.

Scritto dal modello di indicizzazione a partire dal testo della issue.