Add mypy type checking support and fix all type errors

[Copilot]

Summary

Adds mypy static type checking via tox and fixes all 243 type errors across 5 Python source files in the python/src/moocore/ package.

Changes

Configuration

• python/pyproject.toml: Updated python_version from 3.11 to 3.12 (required by current numpy 2.x stubs which use type statement syntax)

Type fixes by file

_docsubstitute.py (3 errors fixed)

• Added TypeVar _T and from typing import Any, TypeVar
• Added -> None to __init__, typed __call__ with _T TypeVar to preserve decorated function types

_ffi_build.py (7 errors fixed)

• Added return type annotations to get_config(), uses_msvc(), _get_target_platform()
• Added list[str] annotation to GCC_LDFLAGS

_datasets.py (4 errors fixed)

• Added path: Path | str type to _file_checksum
• Used .is_file() instead of .exists() (Traversable interface)
• Added cast(Path, ...) for return type narrowing
• Added **kwargs: Any to get_dataset

_utils.py (23 errors fixed)

• Rewrote asarray_maybe_copy with explicit np.ndarray annotation
• Fixed np2d_to_double_array and np1d_to_c_array to avoid ArrayLike attribute access
• Wrapped unique_nosort return in np.asarray()
• Fixed is_integer_value to return bool

_moocore.py (206 errors fixed)

• Added -> None to _check_dimension_max
• Fixed read_datasets to use os.fsdecode (always returns str)
• Changed _parse_maximise_to_bool_array return type to Any (cffi CData)
• Renamed maximise → maximise_arr after _parse_maximise() calls in all functions to avoid type reassignment conflicts
• Wrapped all C library float returns with float()
• Fixed ArrayLike parameters being accessed with .shape, .min(), etc. by converting to np.ndarray first
• Fixed ideal: ArrayLike = None → ideal: ArrayLike | None = None in multiple functions
• Fixed idx reassignment conflicts by renaming to idx_sort/idx_groups
• Added **kwargs: Any to apply_within_sets
• Added type annotations to private functions (get_ideal, generate_ndset helpers)
• Fixed _avg_hausdorff_dist_python to pass maximise correctly to _igd_python

[MLopez-Ibanez]

@copilot rebase on main branch, fix conflicts preferring the version in main always and revise your changes.

I don't want to have a whole python/stub_gen.py script. The few missing stubs that cffi-stubgen cannot handle should be added explicitly. The generated stubs should also be added to the PR so they are committed to the repository.

[Copilot]

@copilot rebase on main branch, fix conflicts preferring the version in main always and revise your changes.

I don't want to have a whole python/stub_gen.py script. The few missing stubs that cffi...

Done. Merged main (preferring main's version in all conflicts), removed stub_gen.py and the stubgen tox env, and committed the stubs directly to python/src/moocore/_libmoocore/lib/__init__.pyi with all 24 C function stubs and the integer constants. All type errors are fixed; tox -e type reports Success: no issues found in 8 source files.