refactor: add android back button

src/index.tsx

@@ -5,6 +5,7 @@ import { HashRouter as Router } from 'react-router-dom';
 import './lib/init-translations';
 import './index.css';
 import './themes.css';
+import { App as CapacitorApp } from '@capacitor/app';
 
 const root = ReactDOM.createRoot(document.getElementById('root') as HTMLElement);
 root.render(
@@ -14,3 +15,12 @@ root.render(
     </Router>
   </React.StrictMode>,
 );
+
+// add back button in android app
+CapacitorApp.addListener('backButton', ({ canGoBack }) => {
+  if (canGoBack) {
+    window.history.back();
+  } else {
+    CapacitorApp.exitApp();
+  }
+});