feat: add rate limiting for CoinGecko API and global error handling

js/app.js

@@ -1,6 +1,10 @@
 import { i18n } from './i18n.js'
+import { setupGlobalErrorHandler } from './components/error-boundary.js'
 
 async function initApp() {
+    // Setup global error handling first
+    setupGlobalErrorHandler()
+
     const savedTheme = localStorage.getItem('theme')
     if (savedTheme) {
         document.documentElement.dataset.theme = savedTheme