The hive policy rendered by policy::render granted every hive cert read
on secret/data/swarm/services/*, which holds each swarm service's OIDC
client secret. No reader of that tree authenticates with a hive cert:
grafana, the otel collector and the store forwarder each read with
their own leaf, and the bao UI's secret is read by the store's granter.
render() now emits two stanzas: swarm/agents/* and the hive's own
swarm/hives/<hive>/*. Kind::Service had no other caller and is removed.
Docs and comments that described the grant as a decision are rewritten
to the current state.
Closes#4960
2505008b83