Custom domain

The session dashboard is served from the API host today: https://email-intel-api-production.up.railway.app/dashboard/. A customer-branded hostname is not a self-serve setting.

Bringing your own domain needs DNS, TLS, and cookie-domain work on the API/dashboard host (tracked internally as JOH-283). Until that ships, do not point a CNAME at the dashboard and expect login to work.