Add LED ring control per client and broadcast over REST and WebSocket.

Solid color mode fills all ring LEDs; master routes UART commands to slaves
via ESPNOW_LED_RING. goTool exposes POST /api/led-ring, WebSocket set_led_ring,
and a dashboard LED panel with master/slave/all targets.

Co-authored-by: Cursor <cursoragent@cursor.com>

main/proto/esp_now_messages.proto

@@ -19,6 +19,7 @@ enum EspNowMessageType {
   ESPNOW_RESTART = 11;
   ESPNOW_ACCEL_SAMPLE = 12;
   ESPNOW_SET_ACCEL_STREAM = 13;
+  ESPNOW_LED_RING = 14;
 }
 
 message EspNowUnicastTest {
@@ -68,6 +69,20 @@ message EspNowAccelSample {
   sint32 z = 4;
 }
 
+/** Master → slave: LED ring command (same modes as UART LedRingProgressRequest). */
+message EspNowLedRing {
+  uint32 client_id = 1;
+  uint32 mode = 2;
+  uint32 progress = 3;
+  uint32 digit = 4;
+  uint32 r = 5;
+  uint32 g = 6;
+  uint32 b = 7;
+  uint32 intensity = 8;
+  uint32 blink_ms = 9;
+  uint32 blink_count = 10;
+}
+
 // Master → slave: begin OTA (erase inactive slot; slave replies ESPNOW_OTA_STATUS).
 message EspNowOtaStart {
   uint32 total_size = 1;
@@ -105,5 +120,6 @@ message EspNowMessage {
     EspNowRestart restart = 12;
     EspNowAccelSample accel_sample = 13;
     EspNowAccelStream accel_stream = 14;
+    EspNowLedRing led_ring = 15;
   }
 }