fix(web): search results panel spans full content width

The header search overlay was anchored to the search bar's width, leaving a
dead strip on the right where scrolling hit the background page. Anchor it to
the sticky #mobile-header instead (which already sits right of the sidebar), so
it spans the full main-content width — sidebar stays visible, no dead strip.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

index.html

@@ -107,10 +107,6 @@
             <svg width="13" height="13" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><circle cx="11" cy="11" r="8"/><path d="m21 21-4.35-4.35"/></svg>
             <input id="header-search-input" type="text" placeholder="Suchen…" oninput="onHeaderSearch(this.value)" autocomplete="off">
             <button id="header-search-clear" onclick="closeHeaderSearch()" style="display:none;background:none;border:none;color:var(--text3);cursor:pointer;font-size:15px;padding:0;line-height:1;flex-shrink:0">✕</button>
-            <!-- Results drop down anchored to the search bar's width (not full-viewport), so the sidebar stays visible -->
-            <div id="header-search-overlay" style="display:none">
-              <div id="header-search-results"></div>
-            </div>
           </div>
           <div style="display:flex;align-items:center;gap:2px;flex-shrink:0">
             <button class="hbtn notif-bell-btn" onclick="toggleNotifPanel()" title="Benachrichtigungen" style="padding:8px;color:var(--text2)">
@@ -122,6 +118,11 @@
             </button>
           </div>
         </div>
+        <!-- Results panel: spans the full main-content width (anchored to the header, which already
+             sits right of the sidebar) so it never covers the sidebar and leaves no dead scroll strip -->
+        <div id="header-search-overlay" style="display:none">
+          <div id="header-search-results"></div>
+        </div>
       </div>
 
       <!-- HOME -->