Custom images for apps added to home

[LXK-98]

Problem

When using "Add to Home" on an app, it appears on the home screen with a capsule showing the app icon scaled up and the background being the app icon as well. It works, but usually looks quite bad.

Proposed Solution

It would be nice to be able to set custom images for those apps (both the capsule and background) from the device's storage. Being able to select them from SteamGridDB would be even better, but it's understandable that it's probably not worth implementing for this rare use case.

Example

[tmgast]

eh, it's more just a lack of built-in data providers and limited free sourcing. For Android apps, Argosy tries to grab metadata and images from the Play Store. If it fails, only the local content is able to be used.

Eventually, I'll add support for local-only usage.. which would require built-in metadata fetching, but there's a lot of technical barriers I'm not ready to deal with for that. Until then, this is just going to be a known gap.