Switch from NeoPixel to FastLED for ESP32-S3 LED reliability

FastLED has better ESP32 support and handles timing/RMT properly.
- Use CRGB array instead of Adafruit_NeoPixel
- FastLED.show() is more reliable on ESP32-S3
- probe command now tests all LEDs at max brightness

src/led_stub.cpp

@@ -19,7 +19,7 @@ void DefaultLedStub::set_mux(PixelStompMux* mux) {
 }
 
 void DefaultLedStub::begin() {
-    Serial.println("[LED] Using WS2812C via PixelStomp MUX");
+    Serial.println("[LED] Using WS2812C via PixelStomp MUX (FastLED)");
     initialized = true;
 
     if (!mux_ptr) {
@@ -30,13 +30,13 @@ void DefaultLedStub::begin() {
     Serial.println("[LED] Startup animation...");
 
     uint32_t colors[] = {
-        0xFF0000,  // Red
-        0x00FF00,  // Green
-        0x0000FF,  // Blue
-        0xFFFF00,  // Yellow
-        0xFF00FF,  // Magenta
-        0x00FFFF,  // Cyan
-        0xFFFFFF,  // White
+        0xFF0000,
+        0x00FF00,
+        0x0000FF,
+        0xFFFF00,
+        0xFF00FF,
+        0x00FFFF,
+        0xFFFFFF,
     };
     int num_colors = sizeof(colors) / sizeof(colors[0]);
 
@@ -51,7 +51,7 @@ void DefaultLedStub::begin() {
         }
         mux_ptr->show();
         Serial.printf("[LED] Colour %d: R=%d G=%d B=%d\n", c, r, g, b);
-        delay(200);
+        delay(300);
     }
 
     clear_all();
@@ -71,15 +71,15 @@ void DefaultLedStub::set_led_state(uint8_t note, uint8_t channel, uint8_t veloci
         led_states[led_index].timestamp = millis();
 
         if (velocity > 0) {
-            uint8_t brightness = map(velocity, 1, 127, 30, 255);
+            uint8_t brightness = map(velocity, 1, 127, 50, 255);
             mux_ptr->set_led_color(led_index, brightness, brightness, brightness);
         } else {
             mux_ptr->set_led_color(led_index, 0, 0, 0);
         }
         mux_ptr->show();
         
-        Serial.printf("[LED] Note %d -> LED %d Ch %d Vel %d (%s)\n",
-                      note, led_index, channel, velocity,
+        Serial.printf("[LED] Note %d -> LED %d Vel %d (%s)\n",
+                      note, led_index, velocity,
                       velocity > 0 ? "ON" : "OFF");
     } else {
         Serial.printf("[LED] Out of range: %d (Note: %d)\n", led_index, note);