Add global brightness control feature with socket handling and UI updates

app.py

@@ -113,6 +113,14 @@ def handle_animation_speed_update(data):
     # Broadcast animation speed update to all clients
     emit('animation_speed_update', data, broadcast=True, include_self=False)
 
+@socketio.on('brightness_update')
+def handle_brightness_update(data):
+    """Handle brightness updates from controller"""
+    print(f'Brightness update received: {data}')
+    print(f'Broadcasting brightness update to {len(connected_clients)} clients')
+    # Broadcast brightness update to all clients
+    emit('brightness_update', data, broadcast=True, include_self=False)
+
 @socketio.on('join_room')
 def handle_join_room(data):
     """Handle client joining a specific room"""