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/zh.json

@@ -186,6 +186,10 @@
   "device.button.remove": "移除",
   "device.button.webui": "打开设备 Web UI",
   "device.button.power_off": "关闭",
+  "device.button.ping": "Ping 设备",
+  "device.ping.online": "在线 ({ms}ms)",
+  "device.ping.offline": "设备离线",
+  "device.ping.error": "Ping 失败",
   "device.power.off_success": "设备已关闭",
   "device.status.connected": "已连接",
   "device.status.disconnected": "已断开",