Ten service modules (forge, matrix chat, authelia, grafana, otel, nats,
swarm-ui, victorialogs, victoriametrics, bao UI) wrote
services.nginx.virtualHosts themselves, each applying the gateway's
listen set, per-name TLS attrs and security headers by hand. They now
declare services.hyperhive.gateway.vhosts.<name> with only their own
locations and options; ./declared-vhosts.nix renders it into the nginx
vhost with listen, TLS and headers added.
An eval assertion refuses a declared vhost that sets listen, addSSL,
onlySSL, enableACME, useACMEHost, sslCertificate or sslCertificateKey,
and one declared while the gateway is off. nats' own leaf is the new
`certificate` field. The rendered nginx vhosts are unchanged.