Reject non-invertible volume affines

[yinkev]

Summary

• reject non-invertible affine matrices during Volume and VolumeGeometry construction
• retain the existing scaled-orthogonality and final-row validation
• clarify the constructor contract and add coverage for both public types

Root cause

The approximate orthogonality check can accept rank-deficient matrices whose dependent column is sufficiently small. Those objects then fail later when spatial operations attempt to invert the affine.

Validation

• regression fails for both constructors on upstream/master
• focused regression: 2 passed
• full tests/test_volume.py: 118 passed
• Flake8 on touched files
• git diff --check

[yinkev]

Replaced by #445 to conform to this repository's documented contributor workflow and branch-naming convention. The replacement uses the same signed commit and identical code diff: #445