Adds tenants/memberships/consent_records tables, a CASL AbilityFactory
keyed on membership role, and a TenantGuard that derives tenant_id from
session only (never client-supplied), per blueprint 8.2/8.3/11.3.
Adds outbox_events + audit_log tables, an OutboxService for transactional
writes, and a Cron-based OutboxDispatcher that publishes pending events
to a BullMQ queue, per blueprint 9.1 (events before intelligence).
