Release v0.9.0

- PyVista as preferred 3D backend with mayavi legacy fallback
- Non-orthogonal cell support via _build_structured_grid
- Fix scipy.integrate.simps compatibility with scipy 1.14+
- Remove Python 2.7 / Canopy references

Co-Authored-By: deepseek-v4-pro

Merge pull request #12 from PytLab/add-poscar-cartesian-coordinate

Make XsdFile compatible with file without lattice info

My version 0.7.11 used in VASP scripts.