fix(gui): Initialize active_tickets in AppController.init_state

The AppController.__getattr__ delegation was returning controller.active_tickets
but init_state() never initialized self.active_tickets, causing an
AttributeError when gui_2.py tried to access self.active_tickets before
controller state was fully loaded.

Fixes live_gui fixture crash in test_mma_concurrent_tracks_stress_sim.py

src/app_controller.py

@@ -1049,6 +1049,7 @@ class AppController:
 
  def init_state(self):
   """Initializes the application state from configurations."""
+  self.active_tickets = []
   self.ui_separate_task_dag = False
   self.ui_separate_usage_analytics = False
   self.ui_separate_tier1 = False