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

tip_calculator/lib/main.dart

@@ -4,7 +4,14 @@ void main() {
   runApp(MaterialApp(title: 'Tip Calculator', home: TipCalculator()));
 }
 
-class TipCalculator extends StatelessWidget {
+class TipCalculator extends StatefulWidget {
+  const TipCalculator({super.key});
+
+  @override
+  State<TipCalculator> createState() => _TipCalculatorState();
+}
+
+class _TipCalculatorState extends State<TipCalculator> {
   double billAmount = 0.0;
   double tipPercentage = 0.0;
 
@@ -49,7 +56,8 @@ class TipCalculator extends StatelessWidget {
                   "Total: \$$total"));
 
           // Show dialog
-          showDialog(context: context, builder: (BuildContext context) => dialog);
+          showDialog(
+              context: context, builder: (BuildContext context) => dialog);
         });
 
     Container container = Container(