The mesh payload didn't include a node's acme domain, so a peer had no way
to build launch URLs for another machine's exposed apps. Publish
gateway_domain in the MQTT registry payload and surface it per-deployment on
/mesh/deployments as `domain`. The dashboard palette and System Map now build
`https://<subdomain>.<domain>` for remote http-exposed apps (references use
their base_url), making primer's apps launchable from civil.
Paul Payne
b28645f2f4