Semantic web density, federation & extraction-friendly primitives

Shipped HTML extraction primitives (HeadingAnchor, DefList, DataTable, Quote, AuthorChip), federated identity (rel=me, WebFinger), AI-readable changelog at /changelog with Atom/JSON feeds, /license page declaring AI-training opt-in with attribution, public chat-knowledge endpoint, OG article extensions, and the program-level GEO audit.