review-doc — reviewable HTML documents with margin comments

What this produces

A single self-contained .review.html file (no network, no deps) that renders a markdown document with:

Google-Docs-style commenting: select text → 💬 → type a note; comments live as cards in a right margin rail, anchored to highlights.
Persistence in localStorage (survives reload, keyed per document).
Export feedback button → downloads <doc>.feedback.md (quoted passages + the user's notes) and a copy-to-clipboard alternative.
General (unanchored) comments, dark/light theme support.

The markdown source stays canonical. Never hand-edit the generated HTML; regenerate it.
Generate: node <dir-containing-this-SKILL.md>/build-review.mjs <source.md> [out.html] (the script sits next to this SKILL.md — use the path you read it from) (default output: <source>.review.html next to the source).
Deliver: open <out.html> on macOS so it lands in the user's real browser (commenting + export need a full browser, not a preview pane), and/or send the file. Tell the user the loop in one line: highlight → comment → Export feedback → give me the file.
When the user returns a *.feedback.md (or pastes its contents): read every quoted passage + note, respond to or apply each one, then regenerate the review HTML from the updated markdown. Existing comments re-anchor by quote; notes on text that changed appear in the rail as "unanchored" rather than being lost.

Works for any markdown: headings, tables, lists, code fences, blockquotes, links, images.
The document id (localStorage key + feedback filename) is derived from the output filename — keep it stable across regenerations so the user's in-progress comments survive.
If the user asks for review docs in some other format, that wins.