Empty commit/PR states no longer auto-return to the menu. Instead, the
user is shown an in-page prompt with a Back option, mirroring the rest
of the CLI: pressing Enter on Back (or ←/backspace) closes the prompt
and returns control to the previous step.
Extract duplicate menu rendering logic from `index.ts` into a new `src/menu.ts` module, providing generic `selectOne` and `selectMany` functions. This reduces code duplication, improves maintainability, and adds consistent UI controls display across the commit flow and platform selection.
Reviewed-on: #3
Add a new `gai pr` subcommand that generates pull request titles and descriptions using AI, then creates the PR via GitHub CLI (`gh`) or Gitea CLI (`tea`). This extends the existing commit-generation system by reusing retry logic and prompt infrastructure, and introduces a `callAI` function that returns raw output (instead of pre-cleaned messages) to support structured PR responses.
Reviewed-on: #2
Mplan