fix: improve duo cli confirm prompt UX

What does this MR do and why?

Fixes two UX issues with the glab duo cli confirm prompts that caused users to accidentally cancel the download/run flow:

1. Wrong default selection — both the download and run confirmation prompts defaulted to No, meaning pressing Enter immediately returned a "download cancelled" or "execution cancelled" error. Both prompts now default to Yes.

2. Unclear button selection — the previous button style used two filled backgrounds (orange vs gray), making it hard to tell which button was focused. The updated style uses a filled orange block for the selected button and plain text for the unselected button, giving a clear visual distinction without any height mismatch.

Screenshots or screen recordings

before	after

How to set up and validate locally

1. Ensure no duo_cli_* config values are set (glab config get duo_cli_auto_download)
2. Run glab duo cli
3. Confirm the download prompt defaults to Yes! and the selected button is clearly distinguishable