Move WLED config tips to footer, add Web UI link, move preview to calibration

- Move WLED Configuration tips from Add Device modal to page footer
- Add WLED Web UI link in footer (auto-populated with first device URL)
- Add WLED Web UI button (globe icon) to device card actions
- Move pixel preview button from device card to calibration modal footer
- Add en/ru i18n keys for new UI elements

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

server/src/wled_controller/static/app.js

@@ -452,6 +452,14 @@ async function loadDevices() {
 
         container.innerHTML = devicesWithState.map(device => createDeviceCard(device)).join('');
 
+        // Update footer WLED Web UI link with first device's URL
+        const webuiLink = document.querySelector('.wled-webui-link');
+        if (webuiLink && devicesWithState.length > 0 && devicesWithState[0].url) {
+            webuiLink.href = devicesWithState[0].url;
+            webuiLink.target = '_blank';
+            webuiLink.rel = 'noopener';
+        }
+
         // Attach event listeners
         devicesWithState.forEach(device => {
             attachDeviceListeners(device.id);
@@ -569,9 +577,11 @@ function createDeviceCard(device) {
                 <button class="btn btn-icon btn-secondary" onclick="showCalibration('${device.id}')" title="${t('device.button.calibrate')}">
                     📐
                 </button>
-                <button class="btn btn-icon btn-secondary" onclick="showPixelPreview('${device.id}')" title="${t('preview.button')}">
-                    👁️
-                </button>
+                ${device.url ? `
+                <a class="btn btn-icon btn-secondary" href="${device.url}" target="_blank" rel="noopener" title="${t('device.button.webui')}">
+                    🌐
+                </a>
+                ` : ''}
             </div>
         </div>
     `;