ekklesiaandClaude Sonnet 5
679a5d225c
Adds Core-owned identity contracts, a Core-owned Better Auth database schema (ekklesia_core_user/session/account/verification), a first-class Core-owned migration source that coexists with module-owned migrations under the exact existing migration system, and an explicit Better Auth construction boundary. No authentication endpoint or sign-in UI is exposed yet (ADR 0010). Co-Authored-By: Claude Sonnet 5 <[email protected]>