feat: add DiscussionEngine with event-driven architecture
- engine.py: DiscussionEngine class with run() and inject_message()
- All print() calls replaced with EventEmitter.emit()
- Event mapping: DISCUSSION_START, ROUND_START, AGENT_TURN_START,
AGENT_MESSAGE, TOOL_CALL, TOOL_RESULT, AGENT_ERROR, ROUND_END,
DISCUSSION_END, BOSS_TURN
- Accepts typed dependencies (APIClient, ToolRegistry, EventEmitter)
- 27 engine tests, all 168 total tests passing
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
vitya
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