Firecracker-class microVMs for dev: 13-microvm-setup.sh (idempotent
installer) + microvm CLI + microvm-net.service (per-user tap pools,
/30s, NAT). Debian 13 cloud assets in /usr/local/lib/microvm/base.
Firecracker v1.16.1 installed but its KVM cap check is refused by this
nested Westmere KVM; qemu -M microvm engine default, FC retry after #601.
Details + UAT: https://projects.knownelement.com/issues/615
