wheel-stub: External Wheel Hosting Backend

wheel-stub is a PEP 517 build backend designed to act as a "soft link" between a package released on a third-party package index and pypi.org. It enables users to maintain the straightforward `pip install foo` experience while the actual wheel files are hosted on a non-PyPI index. The current version is 0.5.0, released on February 6, 2026, and typically follows a needs-based release cadence.