Add manual ping/health check button to device cards

Adds a refresh icon button on each device card that triggers an immediate
health check via POST /devices/{id}/ping, showing online status with
latency or offline result as a toast notification.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/static/locales/ru.json

@@ -186,6 +186,10 @@
   "device.button.remove": "Удалить",
   "device.button.webui": "Открыть веб-интерфейс устройства",
   "device.button.power_off": "Выключить",
+  "device.button.ping": "Пинг устройства",
+  "device.ping.online": "Онлайн ({ms}мс)",
+  "device.ping.offline": "Устройство недоступно",
+  "device.ping.error": "Ошибка пинга",
   "device.power.off_success": "Устройство выключено",
   "device.status.connected": "Подключено",
   "device.status.disconnected": "Отключено",