feat: timer scrobble (12s), artist topsong star+menu, play count toggle

Scrobbling:
- Replace end-of-track scrobble with 12s timer approach
- Android: schedule on onTrackChanged, cancel on pause
- Web: schedule in playCurrent, cancel in togglePlay pause + onEnded
- Skip/new track resets the timer automatically (new song ID)

Artist top songs:
- Add star button and 3-dots context menu to every top song row
- Topsong grid expanded to 5 columns to fit action buttons

Settings — play count toggle:
- New "Bibliothek" section with toggle switch
- When on: shows play count in album/playlist song rows
- Artist page always shows play count regardless of toggle
- Persisted in ns_cfg localStorage

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

index.html

@@ -616,6 +616,17 @@
         </div>
         <span id="abs-s-status" style="font-size:12px;color:var(--green);display:block;margin-top:6px;min-height:16px"></span>
       </div>
+      <div class="settings-section">
+        <h3 style="display:flex;align-items:center;gap:8px;margin-bottom:12px">
+          <span style="width:24px;height:24px;border-radius:6px;background:var(--surface2);display:inline-flex;align-items:center;justify-content:center;font-size:12px">📊</span>
+          Bibliothek
+        </h3>
+        <div class="edit-pl-toggle-row">
+          <span>Abspielhäufigkeit anzeigen</span>
+          <div id="s-show-playcount" class="toggle" onclick="this.classList.toggle('on')"></div>
+        </div>
+        <div class="hint" style="margin-top:6px">Zeigt Wiedergabezahl in Album- und Playlist-Ansichten. Künstlerseite zeigt sie immer.</div>
+      </div>
       <div class="settings-section">
         <h3 style="display:flex;align-items:center;gap:8px;margin-bottom:12px">
           <span style="width:24px;height:24px;border-radius:6px;background:var(--surface2);display:inline-flex;align-items:center;justify-content:center;font-size:12px">🎨</span>