fix(mma): Unblock visual simulation - event routing, loop passing, adapter preservation

Three independent root causes fixed:
- gui_2.py: Route mma_spawn_approval/mma_step_approval events in _process_event_queue
- multi_agent_conductor.py: Pass asyncio loop from ConductorEngine.run() through to
  thread-pool workers for thread-safe event queue access; add _queue_put helper
- ai_client.py: Preserve GeminiCliAdapter in reset_session() instead of nulling it

Test: visual_sim_mma_v2::test_mma_complete_lifecycle passes in ~8s

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ai_client.py

@@ -295,7 +295,6 @@ def reset_session() -> None:
  _gemini_cache_created_at = None
  if _gemini_cli_adapter:
   _gemini_cli_adapter.session_id = None
- _gemini_cli_adapter = None
  _anthropic_client = None
  with _anthropic_history_lock:
   _anthropic_history = []