Set up Ruff, pre-commit hooks, and dev tooling

[zamax14]

Summary

• Adds Ruff and pre-commit to the development extra.
• Adds Ruff config based on the ETL_SIEEJ setup, scoped to unused imports and redefinitions.
• Adds CI for Ruff check and pytest across Python 3.10, 3.11, and 3.12.
• Makes __version__ resolve from package metadata with a fallback for local source checkouts.
• Removes only the unused imports needed for the new Ruff check to pass; this avoids global formatting churn while other feature issues are being reviewed.

Tests

• .venv/bin/ruff check .
• .venv/bin/python -m pytest
• .venv/bin/pre-commit run ruff --all-files
• .venv/bin/pre-commit run trailing-whitespace --all-files
• .venv/bin/pre-commit run end-of-file-fixer --all-files
• .venv/bin/pre-commit run check-yaml --all-files
• .venv/bin/pre-commit run check-merge-conflict --all-files

Notes

• ruff-format is installed as a pre-commit hook, but this PR intentionally does not run a repository-wide format to avoid conflicts with the other issue branches being reviewed in parallel.