Produce tools for content items, which check each download item on upload for correctness

Also ensure the same tools are downloadable for use by developers on their own devices

e.g. wallpapers (check if just a jpg, or a zip, check if zip is a kpackage and check if correct kpackage)
e.g. comics (check if just a pdf, or an epub (check correctness), check of cbr file (check various details, warn if no cover page but still accept if missing, check for acbf data (potentially use to fill out description?))