feat: Neuer-Chat-Button im Chat-Header

Reload-Button (kreisförmiger Pfeil) neben dem Schließen-Button.
Wird erst sichtbar nach der ersten Nachricht. Setzt Konversation
zurück, leert den Verlauf und zeigt die Begrüßung erneut.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/static/dashboard.html

@@ -591,7 +591,12 @@
     <div class="chat-window" id="chat-window">
         <div class="chat-header">
             <span class="chat-header-title">AegisSight Assistent</span>
-            <button class="chat-header-close" id="chat-close-btn" title="Schliessen" aria-label="Chat schliessen">&times;</button>
+            <div class="chat-header-actions">
+                <button class="chat-header-btn chat-reset-btn" id="chat-reset-btn" title="Neuer Chat" aria-label="Neuen Chat starten" style="display:none">
+                    <svg viewBox="0 0 24 24" width="15" height="15"><path d="M17.65 6.35A7.958 7.958 0 0012 4c-4.42 0-7.99 3.58-7.99 8s3.57 8 7.99 8c3.73 0 6.84-2.55 7.73-6h-2.08A5.99 5.99 0 0112 18c-3.31 0-6-2.69-6-6s2.69-6 6-6c1.66 0 3.14.69 4.22 1.78L13 11h7V4l-2.35 2.35z" fill="currentColor"/></svg>
+                </button>
+            <button class="chat-header-btn chat-header-close" id="chat-close-btn" title="Schließen" aria-label="Chat schließen">&times;</button>
+            </div>
         </div>
         <div class="chat-messages" id="chat-messages"></div>
         <form class="chat-input-area" id="chat-form" autocomplete="off">
@@ -613,7 +618,7 @@
     <script src="/static/js/components.js?v=20260304h"></script>
     <script src="/static/js/layout.js?v=20260304h"></script>
     <script src="/static/js/app.js?v=20260304h"></script>
-    <script src="/static/js/chat.js?v=20260315a"></script>
+    <script src="/static/js/chat.js?v=20260315b"></script>
     <script>document.addEventListener("DOMContentLoaded",function(){Chat.init()});</script>
 
     <!-- Map Fullscreen Overlay -->