Support custom tool entrypoints

[konstin]

The package build doesn't install an entrypoint, you are supposed to call it as pythom -m build instead. pipx run build . while uv tool run build . fails. We should support whatever workaround pipx is using, too.

[charliermarsh]

I think build implements this special entrypoint thing for pipx exactly: https://github.com/pypa/build/blob/46337d95bcb6be84eb2b0416cff5bf51ba70d9c5/pyproject.toml#L84

[njzjz]

Workaround:

uv tool run --with build --from build python -m build

One may also want to use uv in the build: (the command is pretty long!)

uv tool run --with build[uv] --from build python -m build --installer uv

[T-256]

Declaring custom entry points would be nice to support those projects didn't expose any entry point names and only allows to use them as module i.e python -m <mod>. I think this could be allowed in cli (which is support multiple use):

# make `cmd` available which runs `mod.__main__`
$ uvx --from pkg --with-script "cmd='mod.__main__'" cmd

Also, for build it turns to:

$ uvx --from build --with-script "build='build.__main__:entrypoint'" build

[charliermarsh]

You can already run uvx --from build pyproject-build

[charliermarsh]

And in the next version, we'll surface that this executable is available, which seems good...