Adds pvecm_quorum_check.sh probe script and wires it into the
checkdefaults system as a new 'quorum' monitoring kind on proxmox-host
entities. Runs every 60s via ssh-script, surfaces unhealthy signal when
cluster loses quorum.
Closes the monitoring blind spot that let the 2026-08-12 3.5h corosync
flapping outage go undetected (ping passed, cluster was non-quorate).
Changes:
- seeds/ontology.yaml: proxmox-host declares monitoring: [quorum]
- internal/checkdefaults/defaults.go: KindQuorum builder
- internal/checkdefaults/build_test.go: 2 new test cases
- checks/pvecm_quorum_check.sh: new probe (deployed to hubris + strong)
- VERSION: 0.30.2 -> 0.31.0
dtoro
7160eee1e1