Adding Python Interface files

[akmazian]

• added .pyi files for type hints in IDEs [Housekeeping] Explicitly typing all files! #303

[iskandr]

Closing this PR — thanks for putting in the work on type stubs! However, maintaining separate .pyi files for every module creates a significant maintenance burden since the stubs will drift from the source code over time with no automated way to keep them in sync. We'd prefer to add inline type annotations incrementally to the source files directly, or at minimum require stubtest validation in CI before adopting stubs. Appreciate the effort!