Remove flash_activity that was stealing focus to LED 0

src/app_task.cpp

@@ -45,9 +45,6 @@ void AppTask::update() {
 void AppTask::process_midi_event(const MidiEvent& event) {
     Serial.printf("[APP] MIDI IN: Type=%d Ch=%d Data1=%d Data2=%d\n",
                   event.type, event.channel, event.data1, event.data2);
-
-    // Flash LED 0 white briefly on ANY MIDI input - visual activity indicator
-    led_driver->flash_activity();
     
     if (event.type == MidiEvent::SYSEX) {
         // Cin is encoded in channel for SYSEX packets