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/vite.config.ts

@@ -0,0 +1,16 @@
+import { defineConfig } from 'vite';
+import react from '@vitejs/plugin-react';
+import tailwindcss from '@tailwindcss/vite';
+
+export default defineConfig({
+  plugins: [react(), tailwindcss()],
+  server: {
+    port: 5173,
+    proxy: {
+      '/api': 'http://localhost:3100',
+    },
+  },
+  build: {
+    outDir: 'dist',
+  },
+});