* feat(systemd): bound spinifex to a resource-limited slice
Add a spinifex.slice parent ceiling (MemoryHigh=80%, MemoryMax=90%,
MemorySwapMax=0) with a spinifex-system.slice child holding the seven
control/infra services, so a runaway hits the slice instead of the host.
A system.slice drop-in (MemoryMin=1G, CPUWeight=300) reserves RAM and CPU
for sshd/journald/the operator, keeping the box reachable when spinifex is
maxed.
The drop-in is generated in setup.sh install_systemd() rather than shipped
as a staged file, since the packaging globs flatten the systemd/ dir; this
mirrors the existing sshd-keygen drop-in pattern. The two .slice files flow
through every staging path unchanged.
Within the single effective cgroup, a slice MemoryMax OOM picks the highest
oom_score victim — guest QEMU (+500) before any service (-500) — so a slice
OOM degrades by killing one guest while the daemon, storage tier, NATS, and
the host all survive.
* feat(setup): provision 8G host swapfile + vm.swappiness=10
Add a setup_swap stage that creates an 8G /swapfile, enables it, persists it
to fstab, and writes vm.swappiness=10 so the kernel only swaps under real
pressure. Backs spinifex.slice MemorySwapMax so the slice can spill to swap
for graceful degradation instead of OOMing a guest. Idempotent; skipped under
ISO_BUILD (firstboot provisions swap on ISO hosts). Reverses the prior swap=0
assumption.
Josh Siviour