upgrade react to v19, migrate from CRA to Vite, add react compiler

src/polyfills.js

@@ -0,0 +1,29 @@
+// Polyfills for Node.js built-ins
+import { Buffer } from 'buffer';
+import process from 'process';
+import 'isomorphic-fetch';
+
+window.Buffer = Buffer;
+window.process = process;
+window.global = window;
+
+// For ethers.js
+window.process.version = ''; // Fake Node.js version
+window.process.env = window.process.env || {};
+
+// Add any missing fetch polyfill
+if (!window.fetch) {
+  console.warn('Fetch API is not available, using polyfill');
+}
+
+// For crypto support
+if (typeof window.crypto === 'undefined') {
+  window.crypto = {};
+}
+if (typeof window.crypto.getRandomValues === 'undefined') {
+  window.crypto.getRandomValues = function (array) {
+    for (let i = 0; i < array.length; i++) {
+      array[i] = Math.floor(Math.random() * 256);
+    }
+  };
+}