Three small UX wins:
1. Onboarding gained step 5 ('Run Teams headless') and step 6 ('Drive from another machine') so new operators discover the auto-launch/auto-hide + LAN-reachable workflows. Existing 'where things live' step renumbered to 7.
2. Settings → DISPLAY → Control surface URL row gains an Open button next to Copy that fires the URL into the default browser via Process.Start with UseShellExecute. Operators previewing how the embedded /ui control panel looks on a phone/tablet no longer need to copy-paste manually.
3. Recording badge in footer now shows 'REC 3 · 12:45' instead of just 'REC 3'. RecordingElapsed VM property maintains a separate timer from the session timer because recording can start AFTER the meeting begins; operators tracking 'how long has the archive copy been rolling' need that distinct duration.
