ci: add check for uv lockfile consistency with pyproject.toml

[psychedelicious]

Summary

ci: add check for uv lockfile consistency with pyproject.toml

Related Issues / Discussions

Inconsistency noted on discord by @keturn:
https://discord.com/channels/1020123559063990373/1049495067846524939/1360297727447011601

QA Instructions

We have an inconsistency, so this PR should fail the check. I'll push a fixed lockfile after it fails, and confirm the updated lockfile lets the check pass.

Merge Plan

Once pushed, we should add this check to the required checks for PR.

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• Documentation added / updated (if applicable)
• Updated What's New copy (if doing a release after this PR)

[psychedelicious]

I triggered the workflow by pushing a change to pyproject.toml, changing the project description. The workflow detected a change to pyproject.toml and ran the check. It failed as expected. I reverted that change, then updated the lockfile. The workflow was triggered by the change to uv.lock and ran the check. It succeeded as expected.

Think this is good to go. Will need @hipsterusername to add the new check to the required checks for merge to main (after this PR merges)