Secondaries reject RFC2136/nsupdate writes, but the read Service round-
robins across all pods. Add an optional per-cluster write endpoint that
targets only the primary pod (ordinal 0) via the StatefulSet pod-name
label. Reads keep using the all-pods Service.
- api: BindCluster.spec.primaryService (*ClusterServiceSpec) — ClusterIP
for in-cluster writers (external-dns) or LoadBalancer for external
- reconcilePrimaryService creates <cluster>-primary selecting pod-0 when
set, deletes it when unset
- regenerate CRDs + install.yaml