Per-region power address, region power-key tool, and two red gates fixed ...

lib-hosts.sh: MAAS power ops originate from the REGION, so the reachable
rack address depends on which region dials. Measured from vr1-dc0-maas-01:
the rack's transit leg 172.31.0.2:22 is CLOSED, its metal-admin leg
10.12.8.2:22 is OPEN. Adds VIRSH_POWER_ADDRESS_FROM_{OFFICE1,DCREGION} for
both DCs (dc1's 10.12.68.2 measured on the dc1 rack, not inferred from
dc0's .2). VIRSH_POWER_ADDRESS still aliases the Office1 form so existing
callers are byte-for-byte unchanged. dc-selector 81 checks; 4 mutations
each killed tests.

New scripts/maas-region-power-key.sh (harness 44/44) installs and verifies
the per-DC MAAS->libvirt key inside a region's snap, ending on a real virsh
call rather than on config. Runbook prerequisite 5 carried this as prose,
and prose is not a gate -- it must also be re-asserted after every snap
refresh. LIVE at dc0: 9/9 exit 0, virsh enumerates 12 domains. The key is
the SEC-012 dc0 key already authorized on that rack, so per-DC isolation
holds.

Three defects its own testing found: ssh-keygen -lf reads an adjacent .pub
and reports ITS fingerprint; a snap's data root (/var/snap) and exec root
(/snap) are not interchangeable; the snap's virsh must run inside the snap
runtime or it fails on missing libraries.

tests/node-vm T8/T9 were RED at HEAD before any of this session's work
(proven by stashing and re-running): commits 086c827 + 447315f added the
region VMs, moving the dc0 root to 11 macs lists / 66 MAC literals against
assertions reading 10 / 60, and the gauntlet was not re-run. Re-pointed to
the new invariant, reason recorded in-file, re-proven able to fail.

HARNESS-MANIFEST re-recorded (91) for the two new harnesses.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HvCyrwvYTTcDYnRErfMsNf