Docker bypasses UFW iptables, so bare port mappings like "5432:5432"
exposed the database to the public internet. Removed port mappings for
PostgreSQL and Redis (they only need Docker-internal networking), and
bound the API port to 127.0.0.1 since only Caddy needs to reach it.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>