feat: app update checker

[tanakrit-d]

Description

A point of friction has been visually reconciling the app version to see if an update is available. Well, be the change you want to see in the world.

I've implemented a simple update checker available from the Library screen. Ideally I would've liked to also add automatic update checking and notifications but that herculean task is quite outside of my skillset at the moment. Baby steps :^)

The user simply presses the refresh button, and any available updates are displayed in the action pill (apologies - unsure of the correct UI terminology here). They can then trigger a download via. the update button.

Screenshots

Testing Notes

I've built and installed the app, and verified the implemented functionality.

[claration]

one of the main problems with an update checker is that we have no way of knowing where the app properly came from, with feather v1 this often caused issues with it getting an entirely different app with the same bundle id.

[tanakrit-d]

Oh. You raise an excellent point.

Could we store metadata for each app and then perform a comparison based on that? This would create a relationship between the source and the app.

Manually added apps would be out of the scope of checking - which also kind of makes sense anyway.