fe9381fc8b
Fix remaining Python 3.9 incompatible type annotations throughout the leann-core package that were causing test failures in CI. The union operator (|) syntax for type hints was introduced in Python 3.10 and causes "TypeError: unsupported operand type(s) for |" errors in Python 3.9. Changes: - Convert dict[str, Any] | None to Optional[dict[str, Any]] - Convert int | None to Optional[int] - Convert subprocess.Popen | None to Optional[subprocess.Popen] - Convert LeannBackendFactoryInterface | None to Optional[LeannBackendFactoryInterface] - Add missing Optional imports to all affected files This resolves all test failures related to type annotation syntax and ensures compatibility with Python 3.9 as specified in pyproject.toml. 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com>