[GuideLLM Refactor] Add tox command to update lock file

[sjmonson]

Summary

Adds a tox env for updating the lock file. Also allows args for mypy env.

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Use of AI

• Includes AI-assisted code completion
• Includes code generated by an AI application
• Includes AI-generated tests (NOTE: AI written tests should have a docstring that includes ## WRITTEN BY AI ##)

[Copilot]

Pull Request Overview

Adds a tox environment to update the dependency lock file with PDM and makes the mypy environment accept additional CLI arguments.

• Allow passing positional arguments to the mypy tox env
• Introduce a new lock tox env that runs pdm lock with update reuse behavior

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