After #21 we can store multiple variants of the same image in the local cache.
We should
[ ] add two download size option:
(already there) download size use for fullscreen image view, populate when shown in full-screen
image thumbnail size: use to download the initial image thumbnail
album thumbnail size: use to download the initial album thumbnail
ideally the thumbnail sizes should be initially auto-selected based on the screen size
[ ] deliver high-resolution variants in a second loop (if needed)
the high resolution variants should be only downloaded if explicitly configured to sync all (#222) or on demand in the fullscreen viewer. In that case we should deliver first the thumbnail variant and after downloading the high resolution variant to update the view.
After #21 we can store multiple variants of the same image in the local cache. We should