The squad parser writes actives element i to club-item slot r15d+i, and r15d
is shared scratch that other atom handlers clobber. Which slots are filled
therefore reveals the index the parse actually started from, which is the
open question behind the regression in vault section 18.
probe_resident_fields.py now prints the slot index of every populated entry
plus the empty ones, and verify_kits.sh runs it next to the map census so one
command reports both residency and whether the squad survived.
funman300