refactor: standardize Dart and Android config across all 54 apps

- Bump all apps to sdk >=3.0.0 <4.0.0 and add flutter_lints + a shared
  analysis_options.yaml to every app (flutter analyze is now green repo-wide)
- Fix real compile errors in firebase_google_authentication and image_editor,
  plus deprecated APIs (Matrix4, SvgPicture.color, textScaleFactor),
  missing async 'mounted' guards, and misc lints via dart fix + manual fixes
- Align pubspec 'name' with each folder and Android namespace/applicationId
  with the documented github.nisrulz.* convention
- Convert bmi_calculator from a legacy Flutter module to a standard app
  with a proper android/ scaffold; fix missing android:exported in launcher
  manifests across 22 apps so all Android builds pass
- Untrack generated build files (GeneratedPluginRegistrant,
  .flutter-plugins-dependencies) and ignore them

using_listview/analysis_options.yaml

@@ -0,0 +1,23 @@
+# Lint rules for Flutter apps.
+# See https://dart.dev/guides/language/analysis-options
+include: package:flutter_lints/flutter.yaml
+
+analyzer:
+  exclude:
+    - build/**
+    - android/**
+    - ios/**
+    - web/**
+    - windows/**
+    - macos/**
+    - linux/**
+
+linter:
+  rules:
+    # Noise in small sample apps; keep the code readable.
+    avoid_print: false
+    avoid_unnecessary_containers: false
+    file_names: false
+    library_private_types_in_public_api: false
+    non_constant_identifier_names: false
+    strict_top_level_inference: false

using_listview/lib/contact_page.dart

@@ -3,7 +3,9 @@ import 'package:using_listview/contactlist/contact_list.dart';
 import 'package:using_listview/contactlist/modal/contact.dart';
 
 class ContactPage extends StatelessWidget {
-  _buildContactList() {
+  const ContactPage({super.key});
+
+  List<ContactModal> _buildContactList() {
     return <ContactModal>[
       const ContactModal(
           fullName: 'Romain Hoogmoed', email: 'romain.hoogmoed@example.com'),

using_listview/lib/contactlist/contact_list.dart

@@ -5,7 +5,7 @@ import 'package:using_listview/contactlist/modal/contact.dart';
 class ContactsList extends StatelessWidget {
   final List<ContactModal> _contactModal;
 
-  ContactsList(this._contactModal);
+  const ContactsList(this._contactModal, {super.key});
 
   @override
   Widget build(BuildContext context) {

using_listview/lib/contactlist/contact_list_item.dart

@@ -4,7 +4,7 @@ import 'package:using_listview/contactlist/modal/contact.dart';
 class ContactListItem extends StatelessWidget {
   final ContactModal _contactModal;
 
-  ContactListItem(this._contactModal);
+  const ContactListItem(this._contactModal, {super.key});
 
   @override
   Widget build(BuildContext context) {

using_listview/pubspec.yaml

@@ -15,6 +15,7 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
+  flutter_lints: ^6.0.0
 
 
 # For information on the generic Dart part of this file, see the