TruckConvertible renders the 4 perimeter edges as wireframe outline.
The scene injects a solid-fill HatchModel for the filled quad using the
existing hatch GPU pipeline (DXF Z-order: p0→p1→p3→p2).
Grippable provides 4 square corner grips; grip moves rebuild the fill model.
PropertyEditable exposes all 4 corners and thickness. Transformable handles
move/rotate/scale/mirror via the standard entity transform path.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
