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

firebase_crash_reporting/lib/main.dart

@@ -4,7 +4,7 @@ import 'package:firebase_core/firebase_core.dart';
 import 'package:firebase_crashlytics/firebase_crashlytics.dart';
 import 'package:flutter/material.dart';
 
-main() {
+void main() {
   WidgetsFlutterBinding.ensureInitialized();
   runZonedGuarded(() {
     runApp(App());
@@ -15,6 +15,8 @@ main() {
 }
 
 class App extends StatelessWidget {
+  const App({super.key});
+
 
   //initialise firebase and crashlytics
   Future<void> _initializeFirebase() async {
@@ -56,6 +58,8 @@ class App extends StatelessWidget {
 }
 
 class CrashApp extends StatelessWidget {
+  const CrashApp({super.key});
+
   @override
   Widget build(BuildContext context) {
     return Center(