Re-land the coverage gate deferred from #343. The Firecracker VM/SSH
orchestration (~230 lines) is only exercised by the integration suite,
which needs /dev/kvm + the provisioned TAP/nft pool — a container runner
skips it and those lines read uncovered, so the 90% diff gate can't pass
on ubuntu-latest. Move the `coverage` job to a self-hosted `kvm` runner
with a firecracker-readiness preflight (binary + /dev/kvm + `backend
status`) so the integration test actually runs. Unit/lint stay on
ubuntu-latest. README documents the runner prerequisites.
Depends on a registered self-hosted runner labelled `kvm`; until one is
provisioned this gate will not run. See PRD 0069 / #348.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WBMWTEtQdJ4W5UrWuLHCck