Modeling Data - Add BRepProp package for modern BRep differential properties (#1116)

Add new BRepProp package to TKBRep as a thin wrapper over GeomProp:: free
functions for computing local differential properties of BRep edges and faces
without exceptions. Replaces the legacy BRepLProp macro-based (.gxx) pattern.

New package BRepProp (TKBRep) provides:
- BRepProp_Curve: Local curve property evaluator for BRep edges.
  Delegates derivative computation to BRepAdaptor_Curve and passes results
  to GeomProp::ComputeTangent, ComputeCurvature, ComputeNormal,
  ComputeCentreOfCurvature. Three Initialize overloads: from TopoDS_Edge
  (owning), from BRepAdaptor_Curve reference (non-owning), and from
  occ::handle<BRepAdaptor_Curve> (shared ownership). Includes static
  Continuity() methods for regularity analysis at curve junctions
  (replaces BRepLProp::Continuity).
- BRepProp_Surface: Local surface property evaluator for BRep faces.
  Delegates derivative computation to BRepAdaptor_Surface and passes results
  to GeomProp::ComputeSurfaceNormal, ComputeSurfaceCurvatures,
  ComputeMeanGaussian. Same three Initialize overloads as BRepProp_Curve.

Key design decisions:
- No variant dispatch needed: BRepAdaptor_Curve/Surface handle geometry-type
  dispatch internally via virtual methods, so BRepProp is a thin wrapper
  calling adaptor D1/D2/D3 then GeomProp:: free functions.
- Ownership pattern: occ::handle for owning case + raw const pointer for
  non-owning case, consistent with GeomProp_Curve/Surface.
- Returns result structs with IsDefined flags instead of throwing exceptions.

18 GTests: 11 unit tests (line, circle, box, cylinder, sphere) and
7 cross-validation tests against BRepLProp_CLProps/BRepLProp_SLProps.

src/ModelingData/TKBRep/BRepProp/BRepProp_Surface.cxx

@@ -0,0 +1,94 @@
+// Copyright (c) 2025 OPEN CASCADE SAS
+//
+// This file is part of Open CASCADE Technology software library.
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License version 2.1 as published
+// by the Free Software Foundation, with special exception defined in the file
+// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
+// distribution for complete text of the license and disclaimer of any warranty.
+//
+// Alternatively, this file may be used under the terms of Open CASCADE
+// commercial license or contractual agreement.
+
+#include <BRepProp_Surface.hxx>
+
+#include <TopoDS_Face.hxx>
+
+//==================================================================================================
+
+void BRepProp_Surface::Initialize(const TopoDS_Face& theFace)
+{
+  if (theFace.IsNull())
+  {
+    myOwned.Nullify();
+    myPtr = nullptr;
+    return;
+  }
+  myOwned = new BRepAdaptor_Surface(theFace);
+  myPtr   = myOwned.get();
+}
+
+//==================================================================================================
+
+void BRepProp_Surface::Initialize(const BRepAdaptor_Surface& theSurface)
+{
+  myOwned.Nullify();
+  myPtr = &theSurface;
+}
+
+//==================================================================================================
+
+void BRepProp_Surface::Initialize(const occ::handle<BRepAdaptor_Surface>& theSurface)
+{
+  myOwned = theSurface;
+  myPtr   = myOwned.get();
+}
+
+//==================================================================================================
+
+GeomProp::SurfaceNormalResult BRepProp_Surface::Normal(const double theU,
+                                                       const double theV,
+                                                       const double theTol) const
+{
+  if (!IsInitialized())
+  {
+    return {{}, false};
+  }
+  gp_Pnt aPnt;
+  gp_Vec aD1U, aD1V;
+  myPtr->D1(theU, theV, aPnt, aD1U, aD1V);
+  return GeomProp::ComputeSurfaceNormal(aD1U, aD1V, theTol);
+}
+
+//==================================================================================================
+
+GeomProp::SurfaceCurvatureResult BRepProp_Surface::Curvatures(const double theU,
+                                                              const double theV,
+                                                              const double theTol) const
+{
+  if (!IsInitialized())
+  {
+    return {};
+  }
+  gp_Pnt aPnt;
+  gp_Vec aD1U, aD1V, aD2U, aD2V, aD2UV;
+  myPtr->D2(theU, theV, aPnt, aD1U, aD1V, aD2U, aD2V, aD2UV);
+  return GeomProp::ComputeSurfaceCurvatures(aD1U, aD1V, aD2U, aD2V, aD2UV, theTol);
+}
+
+//==================================================================================================
+
+GeomProp::MeanGaussianResult BRepProp_Surface::MeanGaussian(const double theU,
+                                                            const double theV,
+                                                            const double theTol) const
+{
+  if (!IsInitialized())
+  {
+    return {};
+  }
+  gp_Pnt aPnt;
+  gp_Vec aD1U, aD1V, aD2U, aD2V, aD2UV;
+  myPtr->D2(theU, theV, aPnt, aD1U, aD1V, aD2U, aD2V, aD2UV);
+  return GeomProp::ComputeMeanGaussian(aD1U, aD1V, aD2U, aD2V, aD2UV, theTol);
+}