Make the registry search live

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

zentrale/public/app.css

@@ -21,6 +21,8 @@
 
 * { box-sizing: border-box; }
 
+[hidden] { display: none !important; }
+
 html { -webkit-text-size-adjust: 100%; }
 
 body {
@@ -176,3 +178,6 @@ input[type="text"]:focus-visible, input[type="password"]:focus-visible { border-
   .fakten { grid-template-columns: 1fr; gap: 0; }
   .fakten dd { margin-bottom: 8px; }
 }
+
+#liste:focus { outline: none; }
+#liste[aria-busy="true"] { opacity: .6; transition: opacity .15s; }