DESIGN maps F1-F5 in the §21 intro, adds the hammer-per-deployment row (user 2026-10-03) to
§21.20 with the batch's official rules and [ASSUMED] items, and rewrites the normative lines:
§3 fenced tiles, §5.3 liftoff, §5.4 fatal / ignoreSelect / redeploy, §5.5 bodies, blocking and
enemy selection, §6.4 onBuy and the item snapshot, §8.2 down row/col, §18.3, §19.7. CHANGELOG
0.1.1, SIM, DATA and PLAYING follow; docs-consistency checks them against the code.