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/App.tsx

@@ -0,0 +1,62 @@
+import { useState, useCallback } from 'react';
+import { useQueryClient } from '@tanstack/react-query';
+import GraphView from './components/GraphView';
+import Sidebar from './components/Sidebar';
+import NodePanel from './components/NodePanel';
+import AddNodeModal from './components/AddNodeModal';
+import LinkModal from './components/LinkModal';
+import Toast from './components/Toast';
+
+export default function App() {
+  const [selectedId, setSelectedId] = useState<string | null>(null);
+  const [showAddNode, setShowAddNode] = useState(false);
+  const [linkFromId, setLinkFromId] = useState<string | null>(null);
+  const [toast, setToast] = useState<string | null>(null);
+  const qc = useQueryClient();
+
+  const refresh = useCallback(() => {
+    qc.invalidateQueries({ queryKey: ['graph'] });
+    qc.invalidateQueries({ queryKey: ['nodes'] });
+  }, [qc]);
+
+  const notify = useCallback((msg: string) => {
+    setToast(msg);
+    setTimeout(() => setToast(null), 3000);
+  }, []);
+
+  return (
+    <div className="flex h-screen w-screen overflow-hidden">
+      <Sidebar
+        selectedId={selectedId}
+        onSelect={setSelectedId}
+        onAddNode={() => setShowAddNode(true)}
+      />
+      <div className="flex-1 relative">
+        <GraphView selectedId={selectedId} onSelect={setSelectedId} />
+      </div>
+      {selectedId && (
+        <NodePanel
+          nodeId={selectedId}
+          onClose={() => setSelectedId(null)}
+          onLink={(id) => setLinkFromId(id)}
+          onRefresh={refresh}
+          onNotify={notify}
+        />
+      )}
+      {showAddNode && (
+        <AddNodeModal
+          onClose={() => setShowAddNode(false)}
+          onCreated={() => { refresh(); notify('Node created'); }}
+        />
+      )}
+      {linkFromId && (
+        <LinkModal
+          fromId={linkFromId}
+          onClose={() => setLinkFromId(null)}
+          onCreated={() => { refresh(); notify('Edge created'); }}
+        />
+      )}
+      {toast && <Toast message={toast} />}
+    </div>
+  );
+}