xcaddy build with caddy-dns/cloudflare for DNS-01 TLS. Host network mode
so Caddy can reach other Docker stacks on localhost. Designed as general
reverse proxy — add new site blocks to Caddyfile for future services.
Deployed to dockerhost:/home/stephan/stacks/caddy/
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
