Rework the README's Pangolin-specific deployment section to cover any
reverse proxy (Nginx, Caddy, Traefik, Pangolin). Add TRUST_PROXY /
X-Forwarded-* guidance and Nginx + Caddy config snippets, keeping
Pangolin as one documented example.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>