This is the first working version of QOL, with cursor, folder icon, music pulse, and scroll edge effect (the blur under toolbars) customisation.

The cursor implementation is currently for me to inject into each compatible AppKit window and make it declare its own Cursor, which is not very good because it only works on some apps and reverts to the old cursor in the dock, menu bar, notification center, etc. So my next version of the cursor customisation will be injecting into WindowServer instead, which is the process that handles all macos windows, which would be a good place to change the cursor once everywhere.