fc3h(ui): slot BackupCard into Maintenance panel above migration card

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/components/settings/MaintenancePanel.vue

@@ -12,6 +12,7 @@
     <MLThresholdSliders class="mt-4" />
     <AllowlistTable class="mt-4" />
     <AliasTable class="mt-4" />
+    <BackupCard class="mt-6" />
     <BrowserExtensionCard class="mt-6" />
     <LegacyMigrationCard class="mt-6" />
   </div>
@@ -23,6 +24,7 @@ import CentroidRecomputeCard from './CentroidRecomputeCard.vue'
 import MLThresholdSliders from './MLThresholdSliders.vue'
 import AllowlistTable from './AllowlistTable.vue'
 import AliasTable from './AliasTable.vue'
+import BackupCard from './BackupCard.vue'
 import BrowserExtensionCard from './BrowserExtensionCard.vue'
 import LegacyMigrationCard from './LegacyMigrationCard.vue'
 </script>