Fix CLI crashing on every invocation when package metadata is missing

[bhuvan-somisetty]

Fixes #173

create_parser() built --version as version=f"osipy {_get_version()}", an f-string, so _get_version() (which calls importlib.metadata.version("osipy")) ran immediately while the parser was being constructed, not lazily when --version was actually passed. main() calls create_parser() unconditionally as its first step, so any environment where osipy isn't installed with discoverable package metadata, a plain source checkout without pip install -e ., PYTHONPATH-based execution on HPC, a container that only copies the osipy/ source dir, crashed the entire CLI with an unhandled PackageNotFoundError. Not just --version, every invocation.

This wasn't hypothetical either, it's exactly why tests/unit/cli/test_config.py and tests/unit/cli/test_wizard.py were failing in a plain checkout before this fix, and none of those failing tests even touch --version.

Fix

_get_version() now catches PackageNotFoundError and returns a fallback string instead of raising. Minimal change, single function.

Testing

• Added TestVersionLookupRegression in tests/unit/cli/test_config.py: confirms _get_version() falls back cleanly, create_parser() no longer raises, and --version still exits 0 with a fallback string when metadata lookup fails.
• pytest tests/unit/cli/ → 175 passed (previously 8 of these failed with PackageNotFoundError in this environment; all pass now).
• Full suite: 786 passed, 40 skipped (GPU/data-dependent), 6 xfailed, 0 failed.
• ruff check / ruff format --check clean on both changed files.
• mypy osipy/cli/main.py clean, no errors on the changed function.

[bhuvan-somisetty]

cc @ltorres6 @MohamedNasser8 for review

[ltorres6]

Thanks for your contribution and for identifying this bug.

The ground truth for the version of the package is stored in osipy/_version.py, so the proper fix here is to switch the _get_version() function to use from osipy._version import __version__.

This also eliminates the need for any monkey patching and should simplify your unit-tests.

If you make those changes I am happy to re-review.