Two bugs caused the remnant finder to miss valid empty regions:
1. RemoveDominated used an 80% overlap-area threshold that incorrectly
removed L-shaped remnants. A tall strip to one side would "dominate"
wide strips above/below it even though they represent different usable
space. Replaced with geometric containment check — only remove a box
if it's fully inside a larger one.
2. FindTieredRemnants split remnants at the obstacle envelope boundary,
and both pieces could fall below minDimension even though the original
remnant passed the filter (e.g., 6.6" remnant split into 5.35" + 1.25"
with minDim=5.38"). Added fallback to keep the original unsplit.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
