Remove all migration logic, scroll tutorial targets into view, mock URL uses device ID

- Remove legacy migration code: profiles→automations key fallbacks, segments array
  fallback, standby_interval compat, profile_id compat, wled→led type mapping,
  legacy calibration field, audio CSS migration, default template migration,
  loadTargets alias, wled sub-tab mapping
- Scroll tutorial step targets into view when off-screen
- Mock device URL changed from mock://{led_count} to mock://{device_id},
  hide mock URL badge on device cards

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

server/src/wled_controller/static/js/features/device-discovery.js

@@ -337,8 +337,7 @@ export async function handleAddDevice(event) {
 
     let url;
     if (isMockDevice(deviceType)) {
-        const ledCount = document.getElementById('device-led-count')?.value || '60';
-        url = `mock://${ledCount}`;
+        url = 'mock://';
     } else if (isSerialDevice(deviceType)) {
         url = document.getElementById('device-serial-port').value;
     } else {