data-model.md: entities, the canonical-amount_sat and derived-availability
invariants, booking lifecycle diagram. event-flow.md: actor/kind map, the
happy-path sequence diagram, why payment is the commit point, and the
check-then-hold concurrency requirement.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019VUQCfdqiLSsFS2jcGnaFD
