[DF-5001 baseline run — ssh session died at the panic (guest down), no output
 flushed back over the pipe. Decisive output captured from the serial console
 (vm.sh log) in panic.txt:]
  miihub: loaded; hw.miihub_fire=1 panics, hw.miihub_fixcheck=1 validates the fix shape
  miihub: ifmedia_init (EMPTY ifm_list -- all PHYs took the 'no media present' branch, parent added nothing)
  miihub: running miibus_mediainit walk verbatim (mii.c:238-244)
  ifmedia_set: no match for 0x0/0xfffffff
  panic: ifmedia_set
  Trace: ifmedia_set() <- miihub_fire() <- sysctl_root <- userland_sysctl <- sys___sysctl
[vm.sh status immediately after: down.  panic.txt = full serial-console capture.]