Implement Enterprise Worth Roadmap (R-139–R-173).

Production hardening: JWT blacklist, TOTP, Pydantic schemas, Prometheus, SSRF fix, CSP, Redis auth, Celery backup — 35 items across P0-P5

Phase 1.2+5.1+6.2+6.5: Book cover upload with resizing, conversion funnel analytics, intent distribution, backup system, CI/CD pipeline