Accept 2xx/3xx on / so next-intl redirect to /en no longer marks the
container unhealthy and blocks nginx from starting.
Co-authored-by: Cursor <cursoragent@cursor.com>
Strip CRLF from entrypoint scripts in backend/frontend images, use Docker
DNS in staging nginx config, and wait for healthy app services before nginx.
Co-authored-by: Cursor <cursoragent@cursor.com>