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/firesSpinner.dart

@@ -3,8 +3,10 @@ import 'package:flutter_spinkit/flutter_spinkit.dart';
 import 'colors.dart';
 
 class FiresSpinner extends StatelessWidget {
+  const FiresSpinner({super.key});
+
   @override
   Widget build(BuildContext context) {
-    return  new SpinKitPulse(color: fires600);
+    return  const SpinKitPulse(color: fires600);
   }
 }