chore: configure pre-commit hooks and format repository

- Add .pre-commit-config.yaml with trailing-whitespace, end-of-file-fixer, check-yaml, ruff, pyink, and pylint
- Fix duplicate keys in base_xl.yml, base21.yml, and ltx2_video.yml
- Update .gitignore to track .pre-commit-config.yaml
- Format files and fix end of file newlines across the repository
- Add pre-commit setup and venv instructions to README.md