Token-Optimierung: Prompt Caching + Tool-Result-Truncation in History

wwwroot/index.html

@@ -144,6 +144,7 @@
       <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="systemPromptBtn">System-Prompt anzeigen</button>
           <button class="header-menu-item" id="archiveBtn">Archivieren</button>
         </div>
       </div>