test: Fix assertions after GUI state unification

- Update test_gui_symbol_navigation.py and test_gui_text_viewer.py to assert against show_windows['Text Viewer'] instead of the deprecated show_text_viewer attribute.
- Increase synchronization wait time in test_visual_sim_gui_ux.py to ensure the GUI loop accurately reflects the mocked MMA status.

tests/test_visual_sim_gui_ux.py

@@ -37,10 +37,10 @@ def test_gui_ux_event_routing(live_gui) -> None:
   'tier_usage': usage,
   'tickets': []
  })
- time.sleep(1)
+ time.sleep(2)
  
  status = client.get_mma_status()
- assert status.get('mma_status') == 'simulating'
+ assert status.get('mma_status') == 'simulating', f"Expected 'simulating', got '{status.get('mma_status')}'"
  assert status.get('tier_usage', {}).get('Tier 1', {}).get('input') == 10
  print("[SIM] Global state update verified.")