What

Running pn --version should print the installed PythonNative version. Today the flag doesn't exist, so the command exits with an argparse error, and there's no quick way to check which version you're running when filing a bug report.

Where to look

• src/pythonnative/cli/pn.py: the parser is assembled in _build_parser() (around line 864). Argparse has built-in support via parser.add_argument("--version", action="version", version=...).
• The version string is available as pythonnative.__version__ (defined in src/pythonnative/__init__.py and kept in sync with pyproject.toml by python-semantic-release). Note that importing the full pythonnative package pulls in platform code, so prefer reading the version lazily or via importlib.metadata.version("pythonnative").

Acceptance criteria

• pn --version prints a version string (for example, pn 0.x.y) and exits 0.
• A test is added to tests/test_cli.py.
• ./scripts/check.sh passes.

Notes for contributors

See CONTRIBUTING.md for setup. Suggested PR title: feat(cli): add --version flag.