The site terrain integration now also configures zone 1 (3 s budget,
seabed under the hull, trench at the groove entrance, reference scan
from the spawn). The actor test uses an 81 x 65 grid with an
off-diagonal bump, checks tile vertices against their field cells and
samples the collision between vertices.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>