(plan) convert original implement plan to mock api

app/api/topology/route.ts

@@ -0,0 +1,10 @@
+import { NextResponse } from 'next/server'
+import { cluster, models, namespaces, nodes } from '@/lib/clusterMock'
+
+/** Mock stand-in for the real atlas `GET /api/topology`. Serves fixture data, not a live cluster. */
+export async function GET() {
+  return NextResponse.json({
+    data: { nodes, namespaces, models },
+    meta: { snapshotAge: cluster.snapshotAge, generation: cluster.generation, truncated: false },
+  })
+}