fix: simplify audiobook sleep timer custom input; update README

- Remove OK button and expand-on-click from sleep timer custom row
- Always show label + plain number input (no spinners, Enter to confirm)
- Update README with all current features (Spotify importer, ABS, lyrics, filters, etc.)

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

index.html

@@ -719,10 +719,9 @@
         <button onclick="absSleepIn(30)">30 Min</button>
         <button onclick="absSleepIn(45)">45 Min</button>
         <button onclick="absSleepIn(60)">60 Min</button>
-        <div id="abs-sleep-custom-row" class="abs-sleep-custom-row" onclick="if(!this.classList.contains('active')){this.classList.add('active');var inp=document.getElementById('abs-sleep-custom-input');inp.value='';inp.focus();}">
-          <span class="abs-sleep-custom-label">Eigene Zeit…</span>
-          <input id="abs-sleep-custom-input" type="number" min="1" max="999" placeholder="Min" onclick="event.stopPropagation()" onkeydown="if(event.key==='Enter'){var v=parseInt(this.value);if(v>0)absSleepIn(v);}">
-          <button onclick="event.stopPropagation();var v=parseInt(document.getElementById('abs-sleep-custom-input').value);if(v>0)absSleepIn(v);">OK</button>
+        <div class="abs-sleep-custom-row">
+          <span class="abs-sleep-custom-label">Eigene Zeit</span>
+          <input id="abs-sleep-custom-input" type="number" min="1" max="999" placeholder="Min" onkeydown="if(event.key==='Enter'){var v=parseInt(this.value);if(v>0)absSleepIn(v);}">
         </div>
       </div>
     </div>