Part of gazebo-tooling/release-tools#1288

Signed-off-by: Jose Luis Rivero <jrivero@honurobotics.com>

Signed-off-by: Jose Luis Rivero <jrivero@osrfoundation.org>
Signed-off-by: Michael Carroll <mjcarroll@intrinsic.ai>
Co-authored-by: Michael Carroll <michael@openrobotics.org>
Co-authored-by: Michael Carroll <mjcarroll@intrinsic.ai>
(cherry picked from commit 6460f7c)

* fix cpplint

Signed-off-by: Steve Peters <scpeters@openrobotics.org>

…724)

Replace the surface-mesh + divergence theorem implementation of
Box::VolumeBelow and Box::CenterOfVolumeBelow with an analytic
inclusion-exclusion formula (Scardovelli-Zaleski / Lehmann-Gekle).

The old VolumeBelow used TrianglesInPlane which relied on exact float
comparison (Plane::Side() == NO_SIDE) and produced wrong volumes for
non-axis-aligned planes. The old CenterOfVolumeBelow returned the
arithmetic mean of vertex positions instead of the volumetric centroid,
which was only correct for axis-aligned cuts.

The new implementation:
- Computes volume analytically via IE3/IE2/IE1 formulas with proper
  dimensional reduction (handles 3D, 2D, 1D, and degenerate cases)
- Computes centroid via first-moment IE formula with F_k functions
  matched to the effective dimensionality
- Keeps TrianglesInPlane for source compatibility (with bug note)
- Fixes Sphere<float> compilation by replacing hardcoded Vector3d
  with Vector3<T>::Zero in VolumeBelow and CenterOfVolumeBelow

Generated-by: Claude Opus 4.6 (1M context)
Signed-off-by: Carlos Agüero <caguero@osrfoundation.org>

…730)

Generated-by: Claude
Signed-off-by: Carlos Agüero <caguero@osrfoundation.org>

Signed-off-by: Carlos Aguero <caguero@honurobotics.com>