DOCFIX-190: second boot bug -- libvirt domains had ACPI disabled (FreeBSD kernel panic) ...

With DOCFIX-188's memory fix in place the guest finally got its 2 GiB, the kernel
reached interrupt initialisation, and hit a SECOND defect the first bug had masked:

  panic: running without device atpic requires a local APIC
  apic_init() ... mi_startup() ... db>

None of the three VM modules emitted a `features` block, so libvirt rendered
`-machine pc-i440fx-noble,...,acpi=off`. FreeBSD gets its local APIC from ACPI's
MADT table and the OPNsense kernel has no atpic fallback, so with ACPI off it has
no usable interrupt controller. The guest parks in the ddb debugger -- which is
the 100%-of-one-core spin, while virsh still reports the domain as "running".

Fix: features = { acpi = true, apic = {} } in opnsense-edge, cloudinit-vm and
node-vm. node-vm matters most long term: MAAS drives power via ACPI signalling,
so without it graceful shutdown / MAAS power-off would never have worked.

Guard S2 added. Like memory_unit, `tofu validate` cannot catch this -- the whole
features block is optional, so its absence is schema-valid. Flag renamed
--static-only (--check-memory-unit kept as a back-compat alias). Harness 4 -> 6
PASS; fixtures/s2-bad PASSES S1 and still FAILS S2, proving the guards catch
independent classes rather than one masking the other.

LIVE RESULT (measured): acpi=on; kernel boots to userland; CPU idle, no spin;
DHCP lease 172.30.1.126 hostname "OPNsense" on office1-wan. Both boot bugs closed.

STILL OPEN: the Configuration Importer did not apply -- OPNsense came up on
factory defaults. The ISO is verified well-formed (ISO9660 OPNSENSE_CFG containing
CONF/CONFIG.XML with our 10.10.0.1). This is the mechanism the module header has
always flagged UNVERIFIED. Do not guess the fix; read the Importer's console
output. The unanswered WAN ping is NOT a fault -- OPNsense blocks inbound on WAN.

Gauntlet-relevant suites green; repo-lint 0 fail; tofu fmt/validate clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y117t1F525ba9r1vXSBETk