clanker pet — optional security hardening follow-ups (Low)

[deucebucket]

From the 2026-06-17 security audit of the pet Space (deucebucket/clanker). Verdict was safe to keep public; these are the remaining Low / optional hardening items.

• CSRF: add an Origin/Referer check on POST /say /care /toy (currently relies on SameSite=lax + JSON content-type + no CORS — low practical risk, mutations are to the shared pet).
• Non-root container: add a USER directive in the Dockerfile (HF already runs Docker reduced-priv; hardening only).
• PRIVACY.md: disclose raw-chat-text retention in the private clanker-audit dataset; consider truncation.
• Deps: pin remaining floating versions + add pip-audit/Trivy to CI.

Already fixed this session: session cookie Secure flag, /say length cap, clanker-soul pinned to commit SHA, huggingface_hub bounded.