Poll for task status changes. Returns status history entries after the given sequence number. Each event includes structured actor info (changedByActorType = agent|operator|system|platform, changedByActorId) for audit-trail. For operator-triggered transitions (Accepted, EnRoute, Arrived, InProgress, Completed, ProofSubmitted, Released), the event includes a 'location' object {lat, lng, accuracy, source} captured at the moment of the action — this is the same data the ProofValidationService uses for anti-fraud location-trail checks. Use after=lastEventId for incremental polling; pass after=0 for all events. Requires authentication.