Pure nushell rule modelled after tailscale/issuebot. Verbs (case-
insensitive, line start): close, closes, closed, fix, fixes, fixed,
resolve, resolves, resolved, updates, for. Same line must contain
'#' or 'github.com', so cross-repo refs (org/repo#N) and full GitHub
URLs are accepted.
Skip tokens: '[bot]' authors, Revert subjects, '#cleanup' lines,
'skip-issuebot' anywhere in the body.
The rule is a pure function over (author, subject, body) so the
25-case fixture suite drives it directly without spawning git.
The lint-range driver walks `git rev-list base..head` and emits
GitHub workflow annotations on failure.
skip-issuebot
