Fix 23 additional lint issues to reduce from 129 to 106 issues

- Add const constructors to @immutable classes (5 issues: prefer_const_constructors_in_immutables)
- Fix nullable value casts in firesApi.dart (3 issues: cast_nullable_to_non_nullable)
- Remove redundant default argument values (2 issues: avoid_redundant_argument_values)
- Make YourLocation immutable with final fields (2 issues: avoid_equals_and_hash_code_on_mutable_classes)
- Update imports and fix formatting

Reduces lint issues from 129 to 106. APK builds successfully (146 MB).

lib/widgets/app_intro_page.dart

@@ -6,25 +6,25 @@ import 'package:flutter/material.dart';
 import '../utils/widget_utils.dart';
 
 class AppIntroItem {
+  AppIntroItem({required this.icon, required this.title, this.subTitle = ''});
+
   final IconData icon;
   final String title;
   final String subTitle;
-
-  AppIntroItem({required this.icon, required this.title, this.subTitle = ''});
 }
 
 typedef void OnIntroFinish(BuildContext context);
 typedef List<AppIntroItem> ListItems(BuildContext context);
 
 abstract class AppIntroPage extends StatelessWidget {
-  static const String routeName = '/appintro';
-  final ListItems items;
-  final OnIntroFinish onIntroFinish;
-
   const AppIntroPage(
       {Key? key, required this.items, required this.onIntroFinish})
       : super(key: key);
 
+  static const String routeName = '/appintro';
+  final ListItems items;
+  final OnIntroFinish onIntroFinish;
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
@@ -63,7 +63,6 @@ class _AppIntroPageSelector extends StatelessWidget {
         theme.textTheme.titleMedium ?? const TextStyle();
 
     return SafeArea(
-      top: true,
       bottom: false,
       child: Column(
         children: <Widget>[
@@ -75,7 +74,8 @@ class _AppIntroPageSelector extends StatelessWidget {
                 icon:
                     const Icon(Icons.close, size: 30.0, color: Colors.black38)),
           ]),
-          Expanded(child: OrientationBuilder(builder: (context, orientation) {
+          Expanded(child: OrientationBuilder(
+              builder: (BuildContext context, Orientation orientation) {
             return IconTheme(
               data: IconThemeData(
                 size: orientation == Orientation.portrait ? 200.0 : 100.0,

lib/widgets/material_app_with_intro.dart

@@ -1,8 +1,13 @@
 import 'package:flutter/material.dart';
+import 'package:meta/meta.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 import 'dart:async';
 
+@immutable
 abstract class MaterialAppWithIntro extends StatelessWidget {
+  const MaterialAppWithIntro(this.name, this.theme, this.routes,
+      this.introWidget, this.continueWidget, this.prefsKey);
+
   final String name;
   final ThemeData theme;
   final Map<String, WidgetBuilder> routes;
@@ -10,9 +15,6 @@ abstract class MaterialAppWithIntro extends StatelessWidget {
   final WidgetBuilder continueWidget;
   final String prefsKey;
 
-  MaterialAppWithIntro(this.name, this.theme, this.routes, this.introWidget,
-      this.continueWidget, this.prefsKey);
-
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
@@ -25,26 +27,26 @@ abstract class MaterialAppWithIntro extends StatelessWidget {
 }
 
 class MaterialAppWithIntroHome extends StatefulWidget {
+  const MaterialAppWithIntroHome(
+      this.introWidget, this.continueWidget, this.prefsKey);
+
   final WidgetBuilder introWidget;
   final WidgetBuilder continueWidget;
   final String prefsKey;
 
-  const MaterialAppWithIntroHome(
-      this.introWidget, this.continueWidget, this.prefsKey);
-
   @override
   _MaterialAppWithIntroState createState() =>
       _MaterialAppWithIntroState(introWidget, continueWidget, prefsKey);
 }
 
 class _MaterialAppWithIntroState extends State<MaterialAppWithIntroHome> {
+  _MaterialAppWithIntroState(
+      this.introWidget, this.continueWidget, this.prefsKey);
+
   final WidgetBuilder introWidget;
   final WidgetBuilder continueWidget;
   final String prefsKey;
 
-  _MaterialAppWithIntroState(
-      this.introWidget, this.continueWidget, this.prefsKey);
-
   @override
   void initState() {
     super.initState();
@@ -63,19 +65,19 @@ class _MaterialAppWithIntroState extends State<MaterialAppWithIntroHome> {
       await prefs.setBool(initialWizardKey, false);
       if (mounted) {
         await Navigator.of(context)
-            .pushReplacement(MaterialPageRoute(builder: introWidget));
+            .pushReplacement(MaterialPageRoute<void>(builder: introWidget));
       }
     } else {
       if (mounted) {
         await Navigator.of(context)
-            .pushReplacement(MaterialPageRoute(builder: continueWidget));
+            .pushReplacement(MaterialPageRoute<void>(builder: continueWidget));
       }
     }
   }
 
   @override
   Widget build(BuildContext context) {
-    return Scaffold(
+    return const Scaffold(
       body: Center(
         child: CircularProgressIndicator(),
       ),

lib/widgets/rounded_btn.dart

@@ -3,15 +3,6 @@ import 'package:flutter/material.dart';
 /// Rounded button widget with icon and text.
 /// Used primarily in the active fires page.
 class RoundedBtn extends StatelessWidget {
-  static const btnRadius = Radius.circular(90.0);
-
-  final IconData icon;
-  final String text;
-  final Color backColor;
-  final Color fontColor;
-  final TextStyle textStyle;
-  final VoidCallback onPressed;
-
   const RoundedBtn({
     required this.icon,
     required this.text,
@@ -42,6 +33,15 @@ class RoundedBtn extends StatelessWidget {
     );
   }
 
+  static const Radius btnRadius = Radius.circular(90.0);
+
+  final IconData icon;
+  final String text;
+  final Color backColor;
+  final Color fontColor;
+  final TextStyle textStyle;
+  final VoidCallback onPressed;
+
   @override
   Widget build(BuildContext context) {
     return SizedBox(
@@ -49,7 +49,7 @@ class RoundedBtn extends StatelessWidget {
         onPressed: onPressed,
         style: ElevatedButton.styleFrom(
           backgroundColor: backColor,
-          shape: RoundedRectangleBorder(
+          shape: const RoundedRectangleBorder(
             borderRadius: BorderRadius.all(btnRadius),
           ),
         ),