EARS requirements for a controller status query (XCE lsid analog): primary identity
(unknown when unelected), answered-by node+role (distinct from cluster view),
configured peers+count, committed config version + content checksum (catch same-version
divergence), term/commit-apply/fenced/cluster-name, failover-aware delivery, test-client
command, and wait-primary switching its probe to it. C tier only.
