[Wikipedia Loves Delpher Portrait gallery] Convert to server-side app

Currently, https://kbnlwikimedia.github.io/GLAMorousToHTML/extras/delpher_humans_q5_gallery.html is fully client-side: once
the HTML is written, filtering, searching, sorting, pagination, and image carousels all run in the browser.

To make this app more scalable - towards 10-100Ks of person-cards, too much for a client-side app - it needs to be converted into a server-side app.

Using Flask?