Istio multi-cluster endpoint-less mesh Service (decoy selector, not omitted)

How to define an endpoint-less "away-cluster" Service for Istio multi-cluster (multi-primary/multi-network) endpoint merge, so cross-cluster traffic to a Service name routes to a REMOTE cluster's pods. Use when: (1) building a federated mesh where a Service must exist in cluster B but have NO local backends so the mesh routes to cluster A's endpoints (e.g. region-pinned writes, a home/away topology); (2) the away cluster ALSO runs real pods that share the normal app label and must NOT be selected; (3) traffic to <svc>.<ns>.svc.cluster.local hits an empty ClusterIP / "connection refused" / lands locally instead of crossing to the remote cluster. Key rule: use a DECOY selec…