Set per-pad LED colors with dim off state

- Pad 0-1: Blue, 2-4: Orange, 5: Red, 6: White, 7: Amber, 8-9: White
- Off state (velocity=0): dim at ~8% brightness instead of black
- On state: full brightness of assigned color
- clear_all() sets dim colors instead of off

src/led_stub.cpp

@@ -142,6 +142,35 @@ static uint32_t velocity_to_color(uint8_t velocity) {
     return launchpad_palette[velocity];
 }
 
+static const uint32_t pad_base_colors[10] = {
+    0x0000FF, // 0: Blue
+    0x0000FF, // 1: Blue
+    0xFFAA00, // 2: Orange
+    0xFFAA00, // 3: Orange
+    0xFFAA00, // 4: Orange
+    0xFF0000, // 5: Red
+    0xFFFFFF, // 6: White
+    0xFFBF00, // 7: Amber
+    0xFFFFFF, // 8: White
+    0xFFFFFF, // 9: White
+};
+
+static void apply_pad_color(uint8_t index, uint8_t velocity) {
+    if (index >= 10) return;
+    uint32_t base = pad_base_colors[index];
+    uint8_t r = (base >> 16) & 0xFF;
+    uint8_t g = (base >> 8) & 0xFF;
+    uint8_t b = base & 0xFF;
+
+    if (velocity == 0) {
+        r = (uint16_t)r * 20 / 255;
+        g = (uint16_t)g * 20 / 255;
+        b = (uint16_t)b * 20 / 255;
+    }
+
+    mux_ptr->set_led_color(index, r, g, b);
+}
+
 DefaultLedStub::DefaultLedStub() : initialized(false) {
     for (int i = 0; i < NUM_LEDS; i++) {
         led_states[i].active = false;
@@ -203,18 +232,14 @@ void DefaultLedStub::begin() {
 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)
+    // Direct index mode (used by CC feedback / pad colors)
     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);
+        apply_pad_color(led_index, 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;
@@ -265,7 +290,7 @@ void DefaultLedStub::clear_all() {
         led_states[i].note = 0;
         led_states[i].channel = 0;
         led_states[i].timestamp = 0;
-        mux_ptr->set_led_color(i, 0, 0, 0);
+        apply_pad_color(i, 0);
     }
     mux_ptr->show();
     Serial.println("[LED] All cleared");