Schedule background in line with dark mode schedule

[pongloongyeat]

Problem

I typically use a light wallpaper during the day and manually switch to a dark wallpaper when dark mode kicks in.

Proposal

Allow the user to choose what wallpaper to set during day and night. This may require some design changes in how the settings is shown to the user since the wallpaper and colour mode selection are on different views.

Prior Art

I think macOS changes to a darker background when dark mode kicks in:

[hanaral]

macOS originally only allowed you to have day and night variants with the Apple original wallpapers that supported it (there were only 2 to begin with). They don't change based on system theme though, they transition throughout the different times of day in the image based on your local time. However, with iOS it is purely based on the dark or light style - which should be extremely trivial to implement. I recommend only having a curated couple of wallpapers to begin with, maybe from stills of time-lapses or edits of the same image (which is what the macOS walls are, if it wasn't already obvious from the unchanging scenery) Here are the day/night variants of the macOS Big Sur walls I used a while back:

☀️ Day	🌑️ Night