feat: add extra_dependencies package annotation

[eloisekp]

Summary

The additive counterpart to ignore_dependencies: injects extra runtime deps
into a resolved package for when published metadata under-declares them.
Added with an empty marker so it applies to all environments, and pulled into
the resolved closure even if nothing else requires it.

Example

# some-pkg needs another-pkg at runtime but doesn't declare it
uv.package(
    name = "some-pkg",
    extra_dependencies = ["[email protected]"],
    workspace = "pypi",
)

[jvolkman]

Thanks! I'll try to figure out the pull request check issues.