Wiki schema

This is an orientation. The authoritative schema — every field, every edge type, the contract maturity lifecycle, entity types (10 at last count), critical-path markers, the page-acceptance checklist, and the registry script — is wiki/README.md in the repo. Treat that file as the source of truth; this page just gets you started.

These invariants are what make the graph navigable and self-checking — the concept behind it is The contract-first knowledge graph. Read wiki/README.md for the full schema before adding a wiki page.