Add complete type hints to all public methods and functions

[moshesham]

Problem

While some files have type hints (e.g., user.py, DataGenerator.py), many functions lack complete type annotations.

Impact

• Reduced code readability
• Harder to catch type-related bugs
• Poor IDE autocomplete support
• Not following modern Python best practices (PEP 484)

Tasks

• Add type hints to infra/logging_config.py
• Add type hints to SQl_answer.py
• Review and complete type hints in infra/AnswerValidator.py
• Review and complete type hints in infra/DataGenerator.py
• Add type hints to all test files
• Run mypy to validate type hints: mypy infra/ --strict
• Update any dynamically typed sections with proper annotations
• Document type hint conventions in CONTRIBUTING.md

Type Hint Guidelines

• Use typing.Optional[T] for nullable types
• Use typing.Union[T1, T2] for multiple allowed types
• Use typing.List[T], typing.Dict[K, V] for collections
• Use typing.Any sparingly, only when truly necessary
• Add return type annotations to all functions
• Use -> None for functions without return value

References

• PROJECT_REVIEW.md Issue Feature/difficulty-system-and-enhancements #4
• PEP 484: https://www.python.org/dev/peps/pep-0484/