Turn /settings/domain into a real Pro-tier feature. Let projects serve their public hub, docs, feedback, roadmap, and changelog from feedback.acme.com or help.acme.com. Flow: admin enters domain, Hollahoop shows DNS records, verifies CNAME/TXT, provisions TLS automatically, and routes requests to the right project.

Needs domain_verifications table, background verifier, certificate/proxy integration depending on hosting stack, canonical URL handling, sitemap/hreflang awareness, and safe fallback if verification fails. Plan-gated through Stripe once billing lands.