v1.5 Admin Web UI

Delivered: Operational admin UI embedded in Fastify — platform admins manage tenants, credentials, and API keys; tenant admins search, inspect, delete, and reissue passes.

Key accomplishments:
- React 19 + Vite 6 SPA served at /admin — CSP-safe, Docker multi-stage, API namespace isolated
- JWT auth with two roles (platform admin / tenant admin); raw key never stored
- Platform admin: tenant CRUD, credential management, API key lifecycle, cert health badges, bulk job monitoring
- Tenant admin: URL-synced pass list (search/sort/filter/paginate), pass detail with delete + reissue-links

See .planning/MILESTONES.md for full details.