v0.4.0 — security hardening pass 2
Security hardening pass 2.
Install setup-token gate (only someone with file-system access can claim the admin account on a fresh public instance), Content-Security-Policy on the dashboard, MCP connector token expiry, OAuth state bound to the browser, visitor-id HMAC, and a zip-slip guard on the self-updater. Completes the security audit (builds on v0.3.9's ingest/headers/checksum hardening).