Spread: better handling for large objects and piles of objects

# Is your feature request related to a problem? Please describe.
Currently bodies larger than 1000 L/kg are not handled well. If they're too large, they disappear entirely. If they're too heavy, when they are harvested all leather, bones, and meat disappears, leaving only scraps of meat and organ to stay under the 1000L tile cap.

# Describe the solution you'd like
Large objects can exist, but cover adjacent tiles. High piles of objects spread out to adjacent tiles instead of disappearing.

# Describe alternatives you've considered
For now, DinoMod is capping monsters at 1000L/1000kg as a hack

# Additional context
Inspired by a bunch of hungry players

No files, tests, or entry points are named. Start by tracing the handling of the 1000 L/kg tile cap and reproduce both oversized bodies disappearing and harvested contents being removed. Done means large objects remain present, and high piles or large objects spread to adjacent tiles without losing their contents.

Written by the indexing model from the issue text.