Python 3.9 reached end-of-life and the codebase uses PEP 604 union
type syntax (str | None) which requires Python 3.10+.
Changes:
- Remove Python 3.9 from CI build matrix
- Update requires-python to >=3.10 in all pyproject.toml files
- Update classifiers to reflect supported Python versions (3.10-3.13)
- Fix OpenMP library linking in DiskANN CMake configuration
- Add timeout protection for HuggingFace model loading to prevent hangs
- Improve embedding server process termination with better timeouts
- Make DiskANN backend default enabled alongside HNSW
- Update documentation to reflect both backends included by default
- Fix ambiguous fullwidth characters (commas, parentheses) in strings and comments
- Replace Chinese comments with English equivalents
- Fix unused imports with proper noqa annotations for intentional imports
- Fix bare except clauses with specific exception types
- Fix redefined variables and undefined names
- Add ruff noqa annotations for generated protobuf files
- Add lint and format check to GitHub Actions CI pipeline
