Backtrack to non-local versions when wheels are missing platform support (#10046)
## Summary
This is yet another variation on
https://github.com/astral-sh/uv/pull/9928, with a few minor changes:
1. It only applies to local versions (e.g., `2.5.1+cpu`).
2. It only _considers_ the non-local version as an alternative (e.g.,
`2.5.1`).
3. It only _considers_ the non-local alternative if it _does_ support
the unsupported platform.
4. Instead of failing, it falls back to using the local version.
So, this is far less strict, and is effectively designed to solve
PyTorch but nothing else. It's also not user-configurable, except by way
of using `environments` to exclude platforms.