Implements getPreviousRunDate() + cache-based tracking in shouldRunNow()
to prevent duplicate dispatch of scheduled jobs when queue delays push
execution past the cron minute. This resilience ensures jobs catch missed
windows without double-dispatching within the same cron window.
Updated scheduled job dispatches to include dedupKey parameter:
- Docker cleanup operations
- Server connection checks
- Sentinel restart checks
- Server storage checks
- Server patch checks
DockerCleanupJob now dispatches on the 'high' queue for faster processing.
Includes comprehensive test coverage for dedup behavior across different
cron schedules and delay scenarios.
