Pin Ruff in pre-commit + add Ruff format to CI

[hallerite]

This PR pins Ruff in .pre-commit-config.yaml to match uv.lock & adds a ruff format check to the CI workflow (.github/workflows/style.yaml), matching the pre-commit hooks. Also runs ruff format to make repo pass the new CI.

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Note

• CI/pre-commit: Pin ruff to v0.13.0 and add a ruff format --check step in /.github/workflows/style.yaml; update .pre-commit-config.yaml to v0.13.0 with ruff-check and ruff-format hooks.
• Code formatting: Apply ruff format across the codebase (line wraps, whitespace, __all__ lists, asserts), no behavioral changes intended.
• Monitor API: Update utils/monitor/base.py so log_final_samples, save_final_summary, and log_distributions are @abstractmethods; add a default close() method. NoOpMonitor implements the required methods.

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