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

expense_planner/lib/widgets/chart_bar.dart

@@ -5,13 +5,13 @@ class ChartBar extends StatelessWidget {
   final double spendingAmount;
   final double spendingPctOfTotal;
 
-  ChartBar(this.label, this.spendingAmount, this.spendingPctOfTotal);
+  const ChartBar(this.label, this.spendingAmount, this.spendingPctOfTotal, {super.key});
 
   @override
   Widget build(BuildContext context) {
     return Column(
       children: <Widget>[
-        Container(
+        SizedBox(
           height: 20,
           child: FittedBox(
             child: Text('\$${spendingAmount.toStringAsFixed(0)}'),
@@ -20,7 +20,7 @@ class ChartBar extends StatelessWidget {
         SizedBox(
           height: 4,
         ),
-        Container(
+        SizedBox(
           height: 60,
           width: 10,
           child: Stack(