…Python scripts

Replaces the primary build orchestration layer with a Python-based system.
Adds core abstractions including BuildManager for step-wise build
persistence/resumption, CMakeArgumentBuilder for managing CMake definitions,
cross-platform venv utilities, subprocess helpers, and pixi environment
integration. Establishes platform-specific base classes that Linux, macOS,
and Windows implementations extend. Restructures CMake layout into modular
BuildWheelsSupport and SuperbuildSupport components. Shell scripts remain
where still required.

Co-authored-by: Hans J. Johnson <[email protected]>

…d Windows

Implements platform build scripts using the new Python infrastructure.
Linux/manylinux builds use dockcross with auditwheel for manylinux
compliance. macOS builds integrate delocate and respect
MACOSX_DEPLOYMENT_TARGET. Windows builds use delvewheel for wheel
repair. Removes legacy shell scripts superseded by the new Python
implementations.

Co-authored-by: Hans J. Johnson <[email protected]>

Adds make_tarballs.sh and integrates tarball generation logic into
build_python_instance_base.py. Supports creating, downloading, and reusing
ITK build caches across Linux, macOS, and Windows, including manylinux
tarball support, arch-specific naming, and a --build-itk-tarball-cache
CLI option. Adds make_windows_zip.ps1 for streamlined Windows wheel
packaging and zip creation.

… 3.9

Removes unused and outdated shell scripts and legacy build utilities
superseded by the new Python build system. Adds pre-commit hooks with
linting applied across the codebase. Drops Python 3.9 support as it is
EOL. Includes README and documentation updates for the new build workflow.

manylinux2014 is not needed for ITK 6. Remove the manylinux2014 image
tag resolution, the manylinux1/manylinux2014 pixi-to-pattern renaming
entries, and update shell script comments to reference _2_28 and _2_34
as the supported manylinux versions.

Addresses review feedback from @thewtex on PR #302.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>