Step 1.1 and 1.2 of novox/hq ADR 0116. The server is a built artifact rather
than the upstream image directly, because it needs an entrypoint of its own:
the host can only recreate a container, and recreating the bus for every
permission change drops every connection and every in-flight ack. nats-server
reloads on SIGHUP by itself, so the config is mounted as a directory (not
digest-tracked, hq issue 103) and the entrypoint watches the one file.
Verified against the real server, not assumed: a user added to the config
connects, a revoked one is refused, both within one poll interval, with the
container's PID and restart count unchanged and "Reloaded: accounts" in its
log.
Two corrections found by checking rather than reading:
- the seat delivers nothing now (hq ADR 0117), and the controller's parser
refused the manifest until it did — "nats claims mesh-broker, whose holder
answers for amqp, and nats does not provide amqp"
- pinned to the multi-arch index digest; the first pin was the amd64
manifest, which builds here and fails on any other architecture
