feat: add ErrorBoundary for graceful crash recovery

- Catches render errors and shows a styled recovery UI instead of blank white screen
- Try Again button re-renders, Reload button refreshes the page
- Error details shown in a collapsible pre block
- Full i18n support (EN/FR)
- Wraps the entire app in main.tsx

src/main.tsx

@@ -1,10 +1,13 @@
 import React from 'react'
 import ReactDOM from 'react-dom/client'
 import App from './App'
+import { ErrorBoundary } from './components/ErrorBoundary'
 import './index.css'
 
 ReactDOM.createRoot(document.getElementById('root')!).render(
   <React.StrictMode>
-    <App />
+    <ErrorBoundary>
+      <App />
+    </ErrorBoundary>
   </React.StrictMode>,
 )