Split from streamlit

This version is the first to contain only package files and be separate from the streamlit app where this code originated.

The earliest package on PyPI is named v3.0.0 to match the version numbering from the repo with the streamlit app.

Streamlit app repo: https://github.com/stroke-optimist/streamlit_lifetime_stroke
PyPI package: https://pypi.org/project/stroke-lifetime/3.0.0/