Design covers ant gravity/physics, unified brush tool, behavioral
priority stack, sand color variation, and config changes. Research
doc captures real ant nest construction patterns for informing
simulation behavior.
Covers GPU Margolus block CA for particle sand, hybrid material
system (shader behaviors + data-driven registry), ant digging/carrying
mechanics, dual camera (side view primary, top-down secondary), and
tiered gravity model (basic -> angle of repose -> pressure propagation).
