Add frontend React app and server components

- Add React frontend with Excalidraw integration (App.jsx, main.jsx)
- Add Express server with MCP protocol support (server.js)
- Update CLI with new functionality (cli.js)
- Add Vite configuration for frontend build
- Update package.json with new dependencies
- Add public assets and build files
- Update .gitignore to exclude build artifacts

vite.config.js

@@ -0,0 +1,27 @@
+import { defineConfig } from 'vite'
+import react from '@vitejs/plugin-react'
+
+export default defineConfig({
+  plugins: [react()],
+  build: {
+    outDir: 'public/dist',
+    rollupOptions: {
+      input: {
+        main: './frontend/index.html',
+      },
+    },
+  },
+  server: {
+    port: 5173,
+    proxy: {
+      '/api': {
+        target: 'http://localhost:3000',
+        changeOrigin: true,
+      },
+      '/health': {
+        target: 'http://localhost:3000',
+        changeOrigin: true,
+      },
+    },
+  },
+})