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/sandbox.dart

@@ -7,31 +7,32 @@ new RandomColorBlock( child
 */
 
 class Sandbox extends StatelessWidget {
+  const Sandbox({super.key});
+
   static const String routeName = '/sandbox';
 
   @override
   Widget build(BuildContext context) {
     //showDialog(context: context, child: builder(context));
     return Scaffold(
-        appBar: new AppBar(
-            title: new TextField(
+        appBar: AppBar(
+            title: TextField(
           autofocus: true,
-          controller: new TextEditingController(text: "kk"),
-          decoration: new InputDecoration(),
-          onSubmitted: (todoText) {},
+          controller: TextEditingController(text: 'kk'),
+          onSubmitted: (String todoText) {},
         )),
-        body: new ElevatedButton(
-            child: new Text('Press'),
+        body: ElevatedButton(
+            child: const Text('Press'),
             onPressed: () {
               showDialog(
                   context: context,
-                  builder: (context) {
-                    return new SimpleDialog(
-                        title: new Text('title'),
+                  builder: (BuildContext context) {
+                    return const SimpleDialog(
+                        title: Text('title'),
                         children: <Widget>[
-                          new Padding(
-                            padding: const EdgeInsets.only(left: 16.0),
-                            child: new Text('hhh'),
+                          Padding(
+                            padding: EdgeInsets.only(left: 16.0),
+                            child: Text('hhh'),
                           ),
                         ]);
                   });