Nginx returns a 503 page when maintenance.on exists. The deploy script
automatically enables/disables maintenance mode around the update.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Consolidate Docker, Nginx, and deploy configs from 5 scattered directories
(docker/, deploy/docker/, deploy/nginx/, script/) into a single infra/ tree
with dev/ and prod/ subdirectories. Update all references in docker-compose,
Makefile, CI workflows, Dockerfiles, and documentation.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
