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/introPage.dart

@@ -1,13 +1,18 @@
 import 'package:comunes_flutter/comunes_flutter.dart';
 import 'package:flutter/material.dart';
 
-import 'homePage.dart';
 import 'generated/i18n.dart';
+import 'homePage.dart';
 
 class IntroPage extends AppIntroPage {
+  IntroPage({super.key})
+      : super(
+            items: _fireItems,
+            onIntroFinish: (BuildContext context) =>
+                Navigator.pushNamed(context, HomePage.routeName));
   static const String routeName = '/intro';
 
-  static final fireItems = (BuildContext context) => <AppIntroItem>[
+  static final _fireItems = (BuildContext context) => <AppIntroItem>[
         AppIntroItem(
             icon: Icons.location_on, title: S.of(context).chooseAPlace),
         AppIntroItem(
@@ -20,11 +25,4 @@ class IntroPage extends AppIntroPage {
             icon: Icons.notifications_active,
             title: S.of(context).alertWhenThereIsAFire)
       ];
-
-  IntroPage({Key? key})
-      : super(
-            items: fireItems,
-            onIntroFinish: (context) =>
-                Navigator.pushNamed(context, HomePage.routeName),
-            key: key);
 }