const MICRO_RUNG_BASE: 32
The rung number the sub-floor ladder starts at.
Thirty-two, which is past any canonical rung a ladder can reach — an
uncapped one bottoms out at nineteen on the largest body in scope and
MAX_CRATER_LEVELS cuts it at fourteen — so a sub-floor crater can never draw
a basin's hashes however the canonical ladder is later extended. The rung
number is the fourth lane of the lattice hash and nothing else.