Change scanner status label "Not yet started" to "Not started"

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/lib/widgets/dhcp_scanner_card.dart

@@ -27,7 +27,7 @@ class DhcpScannerCard extends StatelessWidget {
     if (!status.isListening) {
       return (
         color: Theme.of(context).colorScheme.outline,
-        label: 'Not yet started',
+        label: 'Not started',
         sublabels: [],
       );
     }