Consolidated two stateless classes into one unified API: Dxf.Import(),
Dxf.GetGeometry(), Dxf.ExportPlate(), Dxf.ExportProgram(). Export
state moved into a private ExportContext. Removed bool+out pattern
from GetGeometry in favor of returning empty list on failure.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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>
