Fix CC feedback: route to correct pixel by LED index

src/app_task.cpp

@@ -112,7 +112,8 @@ void AppTask::process_midi_event(const MidiEvent& event) {
             led_driver->set_led_state(
                 pad_mapping[led_index].midi_note,
                 pad_mapping[led_index].midi_channel,
-                cc_val
+                cc_val,
+                led_index
             );
             Serial.printf("[APP] CC -> LED: Ch%d CC%d Val%d -> LED%d\n",
                           midi_channel, cc_num, cc_val, led_index);

src/led_stub.cpp

@@ -200,9 +200,27 @@ void DefaultLedStub::begin() {
     Serial.println("[LED] Startup complete");
 }
 
-void DefaultLedStub::set_led_state(uint8_t note, uint8_t channel, uint8_t velocity) {
+void DefaultLedStub::set_led_state(uint8_t note, uint8_t channel, uint8_t velocity, int8_t led_index) {
     if (!initialized || !mux_ptr) return;
 
+    // Direct index mode (used by CC feedback)
+    if (led_index >= 0 && led_index < NUM_LEDS) {
+        led_states[led_index].active = (velocity > 0);
+        led_states[led_index].note = note;
+        led_states[led_index].channel = channel;
+        led_states[led_index].velocity = velocity;
+        led_states[led_index].timestamp = millis();
+        uint32_t color = velocity_to_color(velocity);
+        uint8_t r = (color >> 16) & 0xFF;
+        uint8_t g = (color >> 8) & 0xFF;
+        uint8_t b = color & 0xFF;
+        mux_ptr->set_led_color(led_index, r, g, b);
+        mux_ptr->show();
+        Serial.printf("[LED] Set LED %d: note=%d ch=%d vel=%d\n", led_index, note, channel, velocity);
+        return;
+    }
+
+    // Note-match mode (used by NOTE_ON/OFF)
     for (int i = 0; i < NUM_LEDS; i++) {
         if (led_states[i].active && led_states[i].note == note) {
             led_states[i].channel = channel;