Region-resolution gate: maas-profile-assert.sh + named dc0 region profile ...

The wrong-REGION hazard is the migration's unrecoverable failure mode: 13
repo scripts default to MAAS_PROFILE=admin, which on voffice1 resolved to
the OFFICE1 region. Against the wrong profile a carve recreate is a silent
no-op that prints PASS, and machine delete destroys the real record.

New scripts/maas-profile-assert.sh asserts which region a profile resolves
to by rack-controller IDENTITY (a machine count is not proof -- two regions
can hold the same number). Harness 20/20; mutation pass found one of its own
assertions could not fail (nameless rack entries were caught by a different
branch) and it was made branch-specific.

Live both directions: admin -> 23 machines / office1 trio (exit 0);
vr1-dc0-region -> 0 machines / hot-kid (exit 0); admin asserted as hot-kid
(exit 1). Capture docs/audit/dc0-region-profile-assert-20260730.txt.

Tunnel voffice1 -> rack -> 10.12.8.6:5240 because no single host has repo +
CLI + new-region reach + NetBox apex reach. Application-layer and
rack-originated, so SEC-010 is not punctured; nothing was rerouted.

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