Feature Request: Randomize wallpapers from folder

I like my wallpapers changing a lot and it would be cool for it to be automated by auto dark mode. It would be cool if you could select a folder for auto dark mode to randomly select a wallpaper from instead of being limited to a single light and dark wallpaper. With this proposed feature, the user would be able to select different folders for dark mode and light mode. I love the app guys; great work!

No files or tests are named. Start by locating the existing wallpaper settings and light/dark wallpaper selection flow, then trace how settings are presented and applied. Done means users can choose separate light and dark folders and the app selects wallpapers from them randomly during automatic theme changes.

Written by the indexing model from the issue text.