Implement activity event emission for witness patrol operations:
- patrol_started: When witness begins patrol cycle
- polecat_checked: When witness checks a polecat
- polecat_nudged: When witness nudges a stuck polecat
- escalation_sent: When witness escalates to Mayor/Deacon
- patrol_complete: When patrol cycle finishes
Also adds refinery merge queue events for future use:
- merge_started, merge_complete, merge_failed, queue_processed
New command: `gt activity emit <event-type>` allows agents to emit
events from CLI. Events write to ~/gt/.events.jsonl for gt feed.
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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