fix: resolve 2 remaining strict analysis errors

- introPage.dart: Convert fireItems to proper static function closure
- mainDrawer.dart: Convert unreadCount int to String for Text widget

lib/privacyPage.dart

@@ -5,9 +5,8 @@ import 'generated/i18n.dart';
 import 'markdownPage.dart';
 
 class PrivacyPage extends MarkdownPage {
-  static const String routeName = '/privacy';
 
-  PrivacyPage(BuildContext context)
+  PrivacyPage(BuildContext context, {super.key})
       : super(
             title: S.of(context).privacyPolicy,
             route: routeName,
@@ -16,4 +15,5 @@ class PrivacyPage extends MarkdownPage {
                 fileName: 'privacy',
                 ext: 'md',
                 lang: Localizations.localeOf(context).languageCode));
+  static const String routeName = '/privacy';
 }