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

todo_list_using_provider/lib/notifiers/todo_list.dart

@@ -1,25 +1,25 @@
 import 'package:flutter/foundation.dart';
-import 'package:flutter_new_provider_todo/models/todo.dart';
+import 'package:todo_list_using_provider/models/todo.dart';
 
 /// This class represents a model
 /// that notify listeners when it has some changes
 class TodoList extends ChangeNotifier {
-  List<Todo> _list = [];
+  final List<Todo> _list = [];
 
   List<Todo> get list => _list;
 
   void add(Todo newItem) {
-    this._list.add(newItem);
+    _list.add(newItem);
     notifyListeners();
   }
 
   void remove(Todo removedItem) {
-    this._list.remove(removedItem);
+    _list.remove(removedItem);
     notifyListeners();
   }
 
   void clearDoneItems() {
-    this._list.removeWhere((Todo element) => element.done);
+    _list.removeWhere((Todo element) => element.done);
     notifyListeners();
   }
 }