Backport algorithmic changes from occ-gordon

[rainman110]

Summary

Backport the occ_gordon curve-network improvements into geoml:

• Handle closed profile/guide networks correctly in Gordon surface interpolation.
• Add a std::vector<Handle(Geom_BSplineCurve)> overload for geoml::interpolate_curve_network.
• Fix the B-spline intersection solver gradient computation and scale normalization.
• Reduce the runtime of curve-network reparametrization by using a faster fitting path.

Changes

• src/geometry/curve-networks/InterpolateCurveNetwork.*
  • Added explicit handling for closed profile/guide networks.
  • Added C2 cleanup for the final Gordon surface.
• src/geoml/surfaces/surfaces.*
  • Added the BSpline-only overload for interpolate_curve_network.
• src/math/IntersectBSplines.cpp
  • Fixed the objective gradient calculation.
  • Normalized the objective by curve scale to improve robustness across differently sized curves.
• src/geometry/BSplineAlgorithms.cpp
  • Reduced the runtime of reparametrizeBSplineContinuouslyApprox by using a cheaper optimization pass.

Notes

This backport is split into separate commits to keep the individual changes reviewable:

Closes #85

[rainman110]

@AntonReiswich I backported my changes in the occ-gordon library to geoml to keep both codes in line. Please check this out

[codecov-commenter]

Codecov Report

❌ Patch coverage is 76.53061% with 23 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.60%. Comparing base (b5c31ee) to head (3f267b6).

Files with missing lines	Patch %	Lines
...eometry/curve-networks/InterpolateCurveNetwork.cpp	75.00%	20 Missing ⚠️
src/geoml/surfaces/surfaces.cpp	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #86      +/-   ##
==========================================
+ Coverage   64.46%   64.60%   +0.13%     
==========================================
  Files          93       93              
  Lines        6880     6952      +72     
==========================================
+ Hits         4435     4491      +56     
- Misses       2445     2461      +16     

Flag	Coverage Δ
api-tests	63.70% <76.53%> (+0.15%)	⬆️
unittests	62.92% <78.94%> (+0.19%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/geometry/BSplineAlgorithms.cpp	92.74% <100.00%> (+0.06%)	⬆️
src/math/IntersectBSplines.cpp	96.79% <100.00%> (+0.16%)	⬆️
src/geoml/surfaces/surfaces.cpp	90.32% <0.00%> (-9.68%)	⬇️
...eometry/curve-networks/InterpolateCurveNetwork.cpp	79.91% <75.00%> (-1.10%)	⬇️

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[AntonReiswich]

Thank you @rainman110!
I will go through it after the 24th of June.