add build analyzer

repl/vite.config.js

@@ -1,10 +1,15 @@
 import { defineConfig } from 'vite';
 import react from '@vitejs/plugin-react';
+import { visualizer } from 'rollup-plugin-visualizer';
 
 // https://vitejs.dev/config/
 export default defineConfig({
   plugins: [react()],
   build: {
     outDir: '../out',
+    sourcemap: true,
+    rollupOptions: {
+      plugins: [visualizer({ template: 'treemap' })],
+    },
   },
 });