Feature/issue 1333 pyproject modernize

[rosspeili]

Moved project metadata from setup.py into pyproject.toml (PEP 621), modeled on qsim: [project] metadata, dynamic version/deps from dev_tools/requirements/deps/*.txt, resources optional extra, and a PEP 735 dev dependency group for uv sync --group dev. Removed setup.py, and updated MANIFEST.in and _version.py accordingly.

Tested with python -m build (sdist + wheel), pip install -e ., and full pytest (2196 passed; 6 Windows-only parallel-test failures also on main), also updated CONTRIBUTING.md to point at pyproject.toml as the canonical config and document the uv sync --group dev workflow.

Intentionally deferred:

• Migrating .pylintrc / other dotfile tool configs into pyproject.toml
• Adding a committed uv.lock (if we want that workflow?)
• Changing CI to use uv sync instead of locked dev_tools/requirements/envs/*.txt (those files and create-env-files.sh are unchanged)

Closes #1333

[gemini-code-assist]

Code Review

This pull request migrates the project's build configuration and metadata from setup.py to pyproject.toml, updating documentation, packaging scripts, and manifest files accordingly. Feedback on the changes suggests correcting the license field format in pyproject.toml to comply with PEP 621 and restoring the missing Apache Software License classifier to maintain parity with the previous setup.

[gemini-code-assist]

Under PEP 621, the license field must be a table containing either a text or file key (e.g., license = {text = "Apache-2.0"}). Providing a plain string is invalid under the PEP 621 specification and can cause validation errors with strict packaging tools.

license = {text = "Apache-2.0"}

[gemini-code-assist]

The classifier "License :: OSI Approved :: Apache Software License" is missing from the classifiers list. To maintain functional equivalence with the original setup.py configuration and ensure proper categorization on PyPI, please include it.

classifiers = [
    "Development Status :: 5 - Production/Stable",
    "Intended Audience :: Developers",
    "Intended Audience :: Education",
    "Intended Audience :: Science/Research",
    "License :: OSI Approved :: Apache Software License",
    "Operating System :: MacOS",
    "Operating System :: Microsoft :: Windows",
    "Operating System :: POSIX :: Linux",
    "Programming Language :: Python :: 3",
    "Programming Language :: Python :: 3.10",
    "Programming Language :: Python :: 3.11",
    "Programming Language :: Python :: 3.12",
    "Programming Language :: Python :: 3.13",
    "Topic :: Scientific/Engineering :: Chemistry",
    "Topic :: Scientific/Engineering :: Quantum Computing",
]

References

1. When migrating configuration, keep the settings functionally equivalent to the original to maintain a clean change history.

[rosspeili]

@mhucka keeping license = "Apache-2.0" (SPDX, PEP 639) per qsim. Adding the License trove classifier back causes setuptools to fail the build (License classifiers have been superseded by license expressions). Verified with python -m build. Should I ignore Gemini assist's recommendations?