clan borgbackup instance: control serves repos, ns1 backs up its
clan.core.state (the KASP keystore at /var/lib/knot) nightly over the
mesh with repokey encryption. ns1 maps the control machine name to its
ZeroTier address so the borg@control repo resolves.
Run `clan vars generate ns1` before deploy to mint the borg keypair.
vmalert on control evaluates rules (declared in git) against VictoriaMetrics and
remote-writes alert state back, so firing alerts show as the ALERTS series in
Grafana. Covers SOA divergence between ns1/ns2, secondary zone expiry, scrape
target down, and root disk full. No notifier yet (notifier.blackhole). Also adds
TODO.md roadmap.
Berwn