BuildOffsets had Width and Length swapped after the Box axis correction
in c5943e2. Horizontal pushes used Length (X) for perpendicular sweep
and Width (Y) for push start — backwards. This caused part2 to start
inside part1's footprint, producing overlapping best-fit pairs.
Added regression test that verifies no kept best-fit pairs overlap.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Move 43 root-level test files into feature-specific subdirectories
mirroring the main codebase structure: Geometry, Fill, BestFit, CutOffs,
CuttingStrategy, Engine, IO. Update namespaces to match folder paths.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
