Publish the Dashboard to GitHub Pages

Purpose: Publish the interactive Unwind dashboard for this scanned project to its own gh-pages branch, so anyone can view it at https://<owner>.github.io/<repo>/unwind/ — no local server needed.

Why a subdir? GitHub Pages serves a project repo at /<repo>/. We publish into an unwind/ subdir of gh-pages and only ever replace that subdir, so an existing gh-pages branch (project docs, Storybook, coverage, …) is never blatted — every sibling file is preserved. A fresh branch is created as an orphan only when none exists.

Graceful fallback: if git, pnpm, or @unwind/core are unavailable, or the project has no GitHub remote / no scan yet, this skill reports what's missing and stops cleanly (run unwind:uw-scan first if there's no scan).

Safety: all git work happens in an isolated worktree — your working tree and current branch are never touched. The push is outward-facing, so it only happens after you confirm the target.