Chat-Page: Archivieren-Button durch 3-Dot-Menü ersetzt

wwwroot/index.html

@@ -122,7 +122,12 @@
     <header>
       <button class="back-btn" id="chatBackBtn">←</button>
       <h1 id="sessionTitle">-</h1>
-      <button class="header-btn" id="archiveBtn">Archivieren</button>
+      <div class="header-menu">
+        <button class="header-menu-trigger" id="chatMenuBtn">⋮</button>
+        <div class="header-menu-dropdown" id="chatMenuDropdown" hidden>
+          <button class="header-menu-item" id="archiveBtn">Archivieren</button>
+        </div>
+      </div>
     </header>
     <div class="meta-bar" id="meta"></div>
     <div id="chat"></div>