- internal/appname: one naming rule (first label, lowercased, [a-z0-9] only)
- internal/registry: host -> app cache built from zero-scale-app ConfigMaps
(hosts key), with direct and legacy-name fallbacks and a 10s TTL
- gateway: units, binaries and config keyed by the app's canonical host, so
secondary hostnames share one process and one config
- reaper reads app config from the registry instead of the API every tick
- zero-scale-ctl writes a hosts key and uses the shared naming rule
