- CastleNATSClient accepts a token; a tls:// server URL makes nats-py verify the
broker against the system CA (trusts the wildcard's Let's Encrypt issuer, no
custom CA needed)
- config: CASTLE_API_NATS_TOKEN; main wires it through
Server side (instance): nats-server.conf gains tls{} (wildcard cert via
expose.tcp.tls) + authorization{token}; clients use tls://castle-nats.<domain>.