simplified code across the app and consolidated duplicated helpers

lib/view/pages/overhang.dart

@@ -17,6 +17,8 @@ class Overhang extends StatefulWidget {
 }
 
 class _OverhangState extends State<Overhang> {
+  late final Future<bool> _reviewAvailable = InAppReview.instance.isAvailable();
+
   @override
   Widget build(BuildContext context) => Scaffold(
     appBar: AppBar(
@@ -48,7 +50,7 @@ class _OverhangState extends State<Overhang> {
         onTap: () => AppRoutes.openQrShare(context),
       ),
       FutureBuilder(
-        future: InAppReview.instance.isAvailable(),
+        future: _reviewAvailable,
         builder: (context, snapshot) {
           String? getPlatformStoreName() {
             if (Platform.isAndroid) return 'Play store';
@@ -60,19 +62,19 @@ class _OverhangState extends State<Overhang> {
               .openStoreListing(appStoreId: '6458789560')
               .then(
                 (value) {
-              if (!context.mounted) return;
-              InfoDialog.show(context, 'Vielen Dank!');
-            },
-            onError: (error) {
-              if (!context.mounted) return;
-              InfoDialog.show(
-                context,
-                error.toString(),
-                copyable: true,
-                title: 'Fehler',
+                  if (!context.mounted) return;
+                  InfoDialog.show(context, 'Vielen Dank!');
+                },
+                onError: (error) {
+                  if (!context.mounted) return;
+                  InfoDialog.show(
+                    context,
+                    error.toString(),
+                    copyable: true,
+                    title: 'Fehler',
+                  );
+                },
               );
-            },
-          );
 
           final ready = snapshot.connectionState == ConnectionState.done;
           return ListTile(
@@ -83,7 +85,7 @@ class _OverhangState extends State<Overhang> {
               (data) => Text('Im $data'),
             ),
             trailing: const Icon(Icons.arrow_right),
-            onTap: !ready ? null : rate
+            onTap: !ready ? null : rate,
           );
         },
       ),