Put the logic in the google sheet and make the script more dumb

At the moment, the logic is duplicated in the google sheet and also in the script.

I vote that the `logic' for choosing a presenter should be done in the google sheet and not in the script. The sheet is more accessible and easier to understand than the python script.

(Even I think this and I love python and hate excel).

Start by locating the Python script and the Google Sheet, then compare where presenter-selection logic is duplicated. Move the selection logic to the sheet so the script no longer duplicates it; done means presenter choices still work with the sheet as the source of truth.

Written by the indexing model from the issue text.