Phase 9: Admin & DevOps — health check, rate limiting, logging, site admin, Docker healthcheck

- Health check endpoint (GET /api/health) with DB probe and uptime
- In-memory sliding window rate limiting on login (10/60s) and register (5/3600s)
- Structured logging with pino (request timing in hooks, Socket.IO events in server.js)
- Site admin dashboard with tenant stats, CRUD, and requireSiteAdmin guard
- Tenant admin enhanced with tag and category management UI
- Docker HEALTHCHECK in Dockerfile and docker-compose.yml
- Backup documentation (docs/backup.md)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Dockerfile

@@ -37,6 +37,11 @@ RUN mkdir -p /app/uploads
 
 EXPOSE 3000
 
+RUN apk add --no-cache curl
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+  CMD curl -f http://localhost:3000/api/health || exit 1
+
 COPY docker-entrypoint.sh ./
 RUN chmod +x docker-entrypoint.sh