update-docs

Update the public-facing documentation surface — README, CHANGELOG, CONTRIBUTING, top-level docs (architecture, audience, comparison, features, licensing, roadmap), docs/guides/, docs/reference/, docs/architecture/, docs/tech/ — to reflect what the in-scope code change means for users. Persona-aware writing per docs/audience.md; assumes the reader is not an expert on internals. Excludes specs and ADRs (those are /update-specs and by-hand respectively). Use this when finishing user-visible work, before opening a PR that adds capability, when a milestone closes, or whenever the user says "update the docs" / "make sure the docs reflect this." Don't wait to be asked — if user-visible work just shipped, suggest running it.