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/esp_now_comm.h

@@ -4,6 +4,7 @@
 #include "app_config.h"
 #include "client_registry.h"
 #include "esp_err.h"
+#include "uart_messages.pb.h"
 
 esp_err_t esp_now_comm_init(const app_config_t *config);
 
@@ -23,6 +24,11 @@ esp_err_t esp_now_comm_send_unicast_test(const uint8_t mac[CLIENT_MAC_LEN],
 esp_err_t esp_now_comm_send_find_me(const uint8_t mac[CLIENT_MAC_LEN],
                                     uint32_t client_id);
 
+/** Master: LED ring command on one slave. */
+esp_err_t esp_now_comm_send_led_ring(const uint8_t mac[CLIENT_MAC_LEN],
+                                     uint32_t client_id,
+                                     const alox_LedRingProgressRequest *req);
+
 /** Master: request reboot on one slave. */
 esp_err_t esp_now_comm_send_restart(const uint8_t mac[CLIENT_MAC_LEN],
                                     uint32_t client_id);