- Arc rendering now respects the normal vector: when normal.z < 0 the
midpoint is placed on the clockwise side so the curve sweeps the right way
- Removed spurious .to_radians() / .to_degrees() round-trips in arc.rs
(angles are already stored in the unit the trig functions expect)
- apply_grip and apply_transform use consistent angle units
- normalize_insert_entity no longer converts arc angles; the old conversion
was only needed by the now-removed .to_radians() call in to_truck
- Added fix_mirrored_arc: swaps arc start/end angles when the INSERT has a
mirrored scale (x_scale * y_scale < 0) so exploded arcs curve correctly
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
