added py-pkg files and updated age_split to have innit

[saalUW]

py-pkg files are not edited for pyDisagg yet but the files have been added so that they can build. Also added innit so that it can work in reticulate

[saalUW]

Added the lint.yml and it is flagging like unused/ ambiguous variables it seems

[zhengp0]

Added the lint.yml and it is flagging like unused/ ambiguous variables it seems

The "error" message from ruff is very informative, I think we can go ahead and remove all the unused imports and change the variable name from l to something more informative :) Here are the messages

src/pydisagg/DisaggModel.py:8:25: F401 [*] `scipy.stats.norm` imported but unused
src/pydisagg/DisaggModel.py:738:9: F841 Local variable `beta` is assigned to but never used
src/pydisagg/__init__.py:9:8: F401 `pydisagg.age_split.helper` imported but unused; consider removing, adding to `__all__`, or using a redundant alias
src/pydisagg/age_split/age_split.py:141:13: E741 Ambiguous variable name: `l`
tests/test_splitting_consistency.py:6:35: F401 [*] `pydisagg.disaggregate.split_datapoint` imported but unused

[zhengp0]

Later on, when working on the documentations, please change all name from pypkg to pydisagg and remove all the documentations that is not relevant.

[zhengp0]

Here are some extra requests

• Please remove the trailing comma after self or m in the __init__ function in module age_split.models
• Please run ruff format . to formatting the code
• Please change the branch name to refactor/py-pkg-update

[zhengp0]

Thanks very much @saalUW! All the changes are looking good! One last thing, please move all information from setup.cfg to pyproject.toml and delete setup.cfg and setup.py.