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/js/app.js

@@ -31,7 +31,7 @@ import {
 import {
     showSettings, closeDeviceSettingsModal, forceCloseDeviceSettingsModal,
     saveDeviceSettings, updateBrightnessLabel, saveCardBrightness,
-    turnOffDevice, removeDevice, loadDevices,
+    turnOffDevice, pingDevice, removeDevice, loadDevices,
     updateSettingsBaudFpsHint, copyWsUrl,
 } from './features/devices.js';
 import {
@@ -211,6 +211,7 @@ Object.assign(window, {
     updateBrightnessLabel,
     saveCardBrightness,
     turnOffDevice,
+    pingDevice,
     removeDevice,
     loadDevices,
     updateSettingsBaudFpsHint,