add an error state and retry button to the image loading card

[ssube]

If an image generation job fails on the server side, the client does not provide good feedback to the user, and the card will usually keep spinning in the loading state forever or until it's cancelled.

The server usually knows when a job has failed, and if that can be safely recorded, it can notify clients. If the client finds out that a job has failed, it should change the loading card to an error card with a retry button.

[ssube]

The retry button is in place, but may not work with requests that need image sources (source/mask) if you refresh before retrying. I'm not sure if that can be fixed.