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>
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