An image build node up 24 days had lost its running kernel's modules to a linux-lts upgrade, so tun
could not load and every RUN line failed in pasta. mesh-build-image now proves the tun device and,
whatever its look refuses, judges its node not eligible (capacity 0 with the reason), so the asks go
to a node that can build them. The kernel module loads tun at boot and declares kernel-modules-hook,
which keeps the running kernel's modules across an upgrade. Needs mesh-sdk fix/ace-tun (Puller.Eligible).
ADR 0508 §9 and §10: systemd-boot gets an entry from the booted command line, GRUB a regenerated menu only when its kernels change, a found kernel-copying hook is taken over, a full boot partition fails loudly.