TokenReview-based caller identity with audience-scoped tokens and exact
resource.system to ServiceAccount bindings, per ops-warden's recommendation.
Deletes the unwired tenant-engine live-roles adapter (T03) and adds
make verify-posture (T05). Source implements A2; running digest is still A0
until promotion, so tenancy.current.A stays 0.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
