Replace polygon boolean clipping with direct entity splitting using
bounding box filtering and exact intersection math. Eliminates Clipper2
precision drift that caused contour gaps (0.0035") breaking area
calculation and ShapeBuilder chaining.
Also fixes SpikeGrooveSplit: spike depth is now grooveDepth + weldGap
(spike protrudes past groove), both V-shapes use same angle formula,
and weldGap no longer double-subtracted from tip depth.
SplitDrawingForm: fix parameter mapping (GrooveDepth direct from nud,
not inflated), remove redundant Spike Depth display, add feature
contour preview and trimmed split lines at feature positions.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Implements the main drawing splitting algorithm that orchestrates splitting
a Drawing into multiple pieces along split lines using Clipper2 polygon
clipping. After clipping, recovers original arcs by matching clipped edges
back to perimeter entities, stitches in feature edges from ISplitFeature
where polygon edges lie on split lines, and normalizes each piece's origin.
Key fix from plan: filters rapid-layer entities before ShapeProfile
construction so cutouts are properly separated from perimeters.
Includes 7 integration tests covering vertical/horizontal splits, three-way
splits, property copying, origin normalization, cutout assignment, and
grid (cross) splits.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
