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_google_authentication/lib/Services/google_auth.dart

@@ -15,10 +15,9 @@ class GoogleSignInProvider extends ChangeNotifier {
     try {
       await googleSignIn.initialize();
       final googleUser = await googleSignIn.authenticate();
-      if (googleUser == null) return;
       _user = googleUser;
 
-      final googleAuth = await googleUser.authentication;
+      final googleAuth = googleUser.authentication;
 
       final credentials = GoogleAuthProvider.credential(
         idToken: googleAuth.idToken,