feat: integration test for single phase polyhedral discretizations

[OmarDuran]

This PR introduces integration tests for single-phase flow on polyhedral meshes, verifying TPFA and MFD discretizations against exact pressure solutions on star-shaped meshes.

Test Coverage:

TPFA Integration Tests: Parameterized on three mesh types (polyhedral_voronoi_complex.vtk, polyhedral_voronoi_lattice.vtk, polyhedral_voronoi_regular.vtk) to ensure machine-precision solutions on regular meshes and highlight TPFA inconsistency on non–k-orthogonal meshes.

MFD Integration Tests: Parameterized for multiple inner product types (TPFA, QuasiTPFA, QuasiRT, Simple, BdVLM), verifying exact pressure solutions on star-shaped meshes.

TPFA vs MFD Consistency Tests: Cross-check that MFD with innerProductType="TPFA" reproduces the same pressure field as the standard TPFA solver on all meshes.

On the Meshes

Voronoi mesh constructed from a 2d lattice

This mesh Includes n-facet polygonal prisms with 4 to 6 facets (n in {4,5,6}).

Voronoi mesh constructed from a cloud of points

This mesh is designed to cover all element types supported by GEOS and include local mesh adaptations. This mesh Includes n-facet polygonal prisms with 3 to 11 facets (n in {3,4,5,6,7,8,9,10,11}).

Regular k-ortogonal mesh

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.13%. Comparing base (4904736) to head (0a2c914).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3780      +/-   ##
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+ Coverage    58.42%   59.13%   +0.70%     
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  Files         1270     1271       +1     
  Lines       109191   109329     +138     
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+ Hits         63798    64651     +853     
+ Misses       45393    44678     -715     

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[Copilot]

Pull Request Overview

This PR introduces comprehensive integration tests for single-phase flow discretizations on polyhedral meshes, validating both TPFA and MFD (Mimetic Finite Difference) solver accuracy against analytical solutions.

• Implements parameterized tests for TPFA and MFD discretizations across multiple mesh types and inner product formulations
• Adds cross-verification tests to ensure consistency between TPFA and MFD solvers when using equivalent configurations
• Includes three polyhedral mesh files (regular, lattice, and complex Voronoi meshes) and corresponding XML input templates

Reviewed Changes

Copilot reviewed 10 out of 13 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
testPolyhedralDiscretizations.cpp	Main test implementation with parameterized test classes for TPFA, MFD, and consistency verification
polyhedral_voronoi_*.vtk	Three VTK mesh files representing different polyhedral geometries for testing
CMakeLists.txt (integration test)	Build configuration for new integration test directory and mesh file copying
CMakeLists.txt (core components)	Updated to include integration tests in build when tests are enabled
incompressible_*.xml	XML input file templates for TPFA and MFD solver configurations

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[herve-gross]

Looks great! My only comment: change the typo in three filenames: consistentcy->consistency.