feat(orbit): show track attribution in host queue + host label in guest queue

Before: the guest queue already labelled guest-suggested tracks with
"Suggested by {user}", but host picks had no label — and the host's own
queue had no attribution at all. The host couldn't tell which upcoming
rows came from guests without checking the pending-approvals list.

- Guest queue: host-pick rows now show "Added by host" instead of hiding
  the attribution line.
- Host queue: each row (and the current track) shows "Added by you" or
  "Added by {user}" while an Orbit session is active. Lookup uses the
  existing OrbitState.queue / currentTrack addedBy field, so no new
  protocol fields.

New i18n keys (en+de+fr+nl+zh+nb+ru+es):
  orbit.queueAddedByHost · queueAddedByYou · queueAddedByUser

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/OrbitGuestQueue.tsx

@@ -169,11 +169,11 @@ export default function OrbitGuestQueue() {
                 <div className="orbit-guest-queue__track-artist">
                   {song?.artist ?? ''}
                 </div>
-                {!isHostPick && (
-                  <div className="orbit-guest-queue__submitter">
-                    {t('orbit.guestSubmitter', { user: q.addedBy })}
-                  </div>
-                )}
+                <div className="orbit-guest-queue__submitter">
+                  {isHostPick
+                    ? t('orbit.queueAddedByHost')
+                    : t('orbit.guestSubmitter', { user: q.addedBy })}
+                </div>
               </div>
             </div>
           );