Release workflow: enforce setuptools_scm version and verify wheel + sdist

[abingham]

Motivation

• Ensure the release build uses the prepared release version and to explicitly verify that both the universal wheel and source distribution are produced and correctly named.

Description

• Add SETUPTOOLS_SCM_PRETEND_VERSION to the Build distribution step set from needs.prepare.outputs.version so setuptools_scm reports the intended release version during build.
• Rename the verification step to Verify distribution version and universal wheel and inject a VERSION env from needs.prepare.outputs.version.
• Replace loose file listing/grep checks with explicit tests for dist/cosmic_ray-${VERSION}-py3-none-any.whl, dist/cosmic_ray-${VERSION}.tar.gz, and assert that exactly two files exist in dist.

Testing

• Locally executed the packaging commands and the new verification commands to confirm the wheel and sdist are produced and named for the prepared version, and the checks succeeded.
• The repository's CI workflow file was updated only for the release job verification and no unit test suite changes were made.

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Codex Task