Reduce an interrupted task log

Implement the documented application state machine in the solution contract: submitted can become working, rejected, or canceled; working can pause for input/authentication or finish; paused work can resume or cancel; terminal work cannot reopen. Events use positive consecutive integer seq values and short internal state names. Identical duplicate events are ignored; conflicting duplicates, gaps, and invalid transitions raise ValueError. Return the final state and sequence. These sequence fields and transition restrictions are teaching policy, not A2A wire requirements.