The swarm-controller builds the Forge quick link from
services.hyperhive.swarm.forge.domain, replacing hive-forge/default.nix's
per-host entry, so all seven swarm-service links come from swarm-level
options.
Also drops the remaining references to the removed matrix GUI switch:
the HiveUrls / Urls / hive_urls docs, the hivectl.md `open` note and
the gateway.md vhost-map rows, which name `gatewayHost` instead. The
grafana, victoriametrics and victorialogs modules' comments no longer
mention a quick-link they do not define.
Refs #4885
72e9e1bb4a