Recover from failed image retrieval

[defagos]

As a user I would like artwork and chapter images to be reloaded automatically after temporary failure (e.g. network).

Acceptance criteria

• Non-loaded images after network failure are reloaded once the network is reachable again.
• Other kinds of errors (404, e.g.) do not lead to major undesired network activity.

Hints

We could use NWPathMonitor to trigger reload when the network is reachable again.

Tasks

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