Add email list sync UI, Phase 4 user fields, and startup migrations.

Add enterprise growth APIs, billing, admin UI, and test suite.

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

Enforce brief sales-focused chatbot rules with spoiler guard and buy CTAs.

Restructure chat flow: hello shows clickable book list, then engaging Q&A.

Humanize bot responses for greetings, catalog questions, and empty RAG retrieval.

Deep audit fix: add missing model columns (blocked, rating, tokens_used, out_of_scope_message, buy_url, preview_url), fix .get() calls, fix ingest doc creation, add track-click endpoint, add column migrations, fix email crash, fix audit log field names, enrich superadmin author list

Fix: specify foreign_keys on User.access_records to resolve AmbiguousForeignKeysError

Restructure project for HF Spaces deployment