Adds 10 new testkit tests covering the relay moderation shadow-queue
and admin relay management endpoints introduced by the moderation
feature:
- T41: GET /api/relay/policy health check
- T42: GET /api/admin/relay/stats field verification
- T43: GET /api/admin/relay/queue list structure
- T44: Invalid status filter → 400
- T45–T46: Approve/reject non-existent event → 404
- T47: Admin grant write access + verify in accounts list
- T48: Admin revoke access
- T49–T50: Input validation guards (invalid pubkey, invalid level)
Admin tests are gated on endpoint accessibility — they skip gracefully
when ADMIN_TOKEN is not set and localhost fallback is unavailable.
Refs #39
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>