v10.11.0.16

Sturdier scans against flaky APIs. Every external service call now retries rate-limit and transient failures (honouring Retry-After) instead of dropping the lookup; a service that keeps failing is set aside for a couple of minutes so the scan moves on to the others rather than stalling; the scan saves its progress to disk as it goes so a crash or restart no longer loses the batch; and every request now identifies the plugin (with its version) to the API.