The Isolation section predated the #16 arc: it described the ACL and the
host firewall, and none of what that audit shipped — port-isolated NICs
(the actual sibling boundary), dns.mode=none, the pinned resolver. It
also never mentioned that the contract is tested at all.
State the contract layer by layer as it exists on main, and add a
'Measured, not claimed' section: the drill and doctor, what each does,
which one mutates the host, and the standing score — 47/47 from a bare
host (run 13, full teardown → rebuild → drill).
