New 292-line test file for structured mesh generation:
- Tests unit cube mesh creation (single and multiple elements)
- Tests structured box mesh with custom dimensions
- Tests uniform spacing verification
- Tests cantilever and thin plate mesh generation
- Tests anisotropic mesh (fine in one direction, coarse in others)
- Tests connectivity validation
- Tests integration with refinement
- Tests convergence study pattern
Comprehensive test suite for structured mesh generation utilities.