Where things are documented

All of it is published as docs.scmjs.dev, built by npm run build:docs (scripts/build-docs.mjs) and deployed by build.yml's docs job on a tag, like the hosted editor. Two halves: these documents split at their ## headings into pages, and the plugin API reference generated from the bundled plugin-api/index.d.ts — so a doc comment in src/plugins/api.ts is a paragraph on the site, and a member with none shows as a bare signature. Nothing on the site is prose a generator wrote, and these files stay where all of it is maintained.