Improve code quality and test robustness:
- Refactor environment variable parsing in rerank config using centralized get_env_value helper
- Add return type hints to all test methods for better type safety
- Fix patch path in test from lightrag.utils to lightrag.rerank for correct import location
- Clarify batch insert endpoint behavior regarding duplicate content rejection
- Expand .dockerignore to comprehensively exclude node_modules (200MB+), Python cache files, and venv directories
- Update dependency groups: align evaluation and test extras with pytest/pre-commit/ruff tools
- Add KaTeX extensions (mhchem for chemistry, copy-tex for copying)
- Add CASCADE to AGE extension for PostgreSQL
- Remove future dependency, replace passlib with bcrypt
- Fix Jina embedding configuration and provider defaults
- Update gunicorn help text and bump API version to 0258
- Documentation and README updates
- Update import from PyPDF2 to pypdf
- Change dependency to pypdf>=6.1.0
- Update all requirements files
- Remove PyPDF2 from lock file
- Use modern pypdf library