An exported GITEA_TOKEN only exists in the shell that exported it, so
tooling invoked from elsewhere could not find it. Resolve in order:
$GITEA_TOKEN, ~/.config/gitea/token, then the macOS Keychain — so the
token can live somewhere durable and non-world-readable instead of a
plaintext dotfile.
Also factors the API call and repo coordinates into scripts/lib/gitea.sh
so pr.sh and review.sh stop duplicating them, and adds
`review.sh --list` for enumerating open PRs.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
