Add docstrings and type hints to extractor.py

[michaelos443]

This PR adds comprehensive docstrings and type hints to the extractor.py module to improve code readability and maintainability. The changes include:

• Added module-level docstring explaining the purpose of the module
• Added type hints to all methods and properties
• Added detailed docstrings to all methods describing their functionality, parameters, and return values
• Maintained the existing functionality without any behavioral changes

These improvements will make the codebase more maintainable and easier to understand for new contributors.

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Pull Request opened by Augment Code with guidance from the PR author