Bug: code includes embedded configuration items and other 'magic' items

The code contains quite a few 'magic' numbers and strings which should be configuration choices.

For example, the size = 50000 parameters in preferences.lua, and the date range { gte = "now-20y" }

These values should be moved into config.lua or a similar location so they can easily be adjusted.

Code should rarely (if ever) contain 'magic' numbers or strings.

Start by reviewing preferences.lua and the referenced config.lua or similar configuration location, then search for other embedded numbers and strings. Move values that are intended as configuration choices into the configuration location and verify that the affected behavior can be adjusted there without changing code.

Written by the indexing model from the issue text.