Create python-type-check.yml

[CRF1408]

Adds a GitHub Action to run mypy on the agents package and scripts, catching type errors in pull requests.

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[!NOTE] Adds a CI workflow to run mypy on relevant Python code in PRs.

• New GitHub Actions workflow python-type-check.yml triggers on changes to agents/**/*.py, scripts/python/**/*.py, pyproject.toml, or the workflow itself
• Sets up Python 3.10, installs project with .[dev], and runs mypy agents scripts/python

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