Cache card cover images

[jm355]

Is your feature request related to a problem? Please describe.

When I open nextcloud deck, the card cover images are blank and take a few seconds to load from the server.

Describe the solution you'd like

I'd like the card cover images to always be visible, even if I'm opening the app after it's been closed, and only change/go away if they were changed or deleted on the server. It seems like just keeping a local copy cached and only changing it as needed based on the server would be better than loading it fresh every time

Describe alternatives you've considered

No response

Additional context

No response