feat: status includes is_admin, gear icon in header for admins

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

frontend/app.js

@@ -181,6 +181,14 @@ async function loadTranscripts() {
   if (data.username) {
     userChip.textContent = data.username;
   }
+  if (data.is_admin) {
+    const gearLink = document.createElement('a');
+    gearLink.href = '/settings';
+    gearLink.className = 'back-btn';
+    gearLink.title = 'Einstellungen';
+    gearLink.textContent = '\u2699';
+    document.querySelector('.header-right').prepend(gearLink);
+  }
   connectWs();
   loadTranscripts();
 })();

frontend/index.html

@@ -68,6 +68,13 @@
       transition: border-color 0.15s, color 0.15s;
     }
     .logout-btn:hover { border-color: var(--red); color: var(--red); }
+    .back-btn {
+      font-size: .75rem; padding: 4px 10px; border-radius: 20px;
+      background: none; border: 1px solid var(--border); color: var(--muted);
+      cursor: pointer; font-family: inherit; text-decoration: none;
+      transition: border-color .15s, color .15s;
+    }
+    .back-btn:hover { border-color: var(--red); color: var(--red); }
     main {
       flex: 1;
       display: flex;