* Geometry: spline arc length converges on tight bends, so LENGTHEN shortens to the target (fixes#705)
* Geometry: cap adaptive spline quadrature (depth 10, 1e-10 relative) so a hostile spline can't make LENGTHEN slow
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Co-authored-by: Brandon Thomas <echelon@gmail.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>