fix(inbounds): hide node UI when no enabled node exists

The Deploy-to selector, node column, node stat row, and node filter all
appeared whenever a node row existed in the DB. Local-only deployments
with no nodes (or only disabled nodes) saw a dropdown that only had
"Local Panel" and a filter that did nothing.

useNodeList now exposes hasActive (any node with enable === true).
Inbounds form and list gate node UI on hasActive instead of map size.

frontend/src/composables/useNodeList.js

@@ -36,7 +36,9 @@ export function useNodeList() {
     return n != null && n.enable && n.status === 'online';
   }
 
+  const hasActive = computed(() => nodes.value.some((n) => n.enable));
+
   onMounted(refresh);
 
-  return { nodes, fetched, refresh, byId, nameFor, isOnline };
+  return { nodes, fetched, refresh, byId, nameFor, isOnline, hasActive };
 }