Add Cortex Portal — web visualization for knowledge graph

Express API server wrapping existing store/graph core with REST endpoints
for nodes, edges, graph, and search. React + Vite portal with React Flow
for interactive graph visualization, Tailwind CSS styling, and full CRUD UI
(sidebar, node panel, add/link modals, search bar, toast notifications).

portal/src/hooks/useNodes.ts

@@ -0,0 +1,9 @@
+import { useQuery } from '@tanstack/react-query';
+import { api } from '../api';
+
+export function useNodes(params?: { kind?: string; status?: string }) {
+  return useQuery({
+    queryKey: ['nodes', params],
+    queryFn: () => api.listNodes(params),
+  });
+}