fix: remove bell+settings from sidebar; preserve backend/api keys on re-login

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

index.html

@@ -47,15 +47,6 @@
           <div class="icon">♫</div>
           <span>Nova<em>Sonic</em></span>
         </div>
-        <div class="header-btns">
-          <button class="hbtn notif-bell-btn" onclick="toggleNotifPanel()" title="Benachrichtigungen">
-            <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><path d="M18 8A6 6 0 0 0 6 8c0 7-3 9-3 9h18s-3-2-3-9"/><path d="M13.73 21a2 2 0 0 1-3.46 0"/></svg>
-            <span class="notif-badge" style="display:none">0</span>
-          </button>
-          <button class="hbtn" onclick="openSettings()" title="Einstellungen">
-            <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><circle cx="12" cy="12" r="3"/><path d="M19.07 4.93a10 10 0 0 1 0 14.14M14.24 9.76a4 4 0 0 1 0 4.48M4.93 4.93a10 10 0 0 0 0 14.14M9.76 9.76a4 4 0 0 0 0 4.48"/></svg>
-          </button>
-        </div>
       </div>
       <div class="search-wrap">
         <div class="search-box" onclick="document.getElementById('search-input').focus()">