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

covid19_mobile_app/lib/main.dart

@@ -4,6 +4,8 @@ import 'screens/home.dart';
 void main() => runApp(MyApp());
 
 class MyApp extends StatelessWidget {
+  const MyApp({super.key});
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(

covid19_mobile_app/lib/screens/countrylist.dart

@@ -8,6 +8,8 @@ import 'dart:convert';
 import 'package:folding_cell/folding_cell.dart';
 
 class CountryList extends StatelessWidget {
+  const CountryList({super.key});
+
   @override
   Widget build(BuildContext context) {
     List<dynamic> results = [];
@@ -31,25 +33,27 @@ class CountryList extends StatelessWidget {
       body: FutureBuilder(
         future: getAllCountriesData(),
         builder: (context, snapshot) {
-          if (snapshot.connectionState == ConnectionState.waiting)
+          if (snapshot.connectionState == ConnectionState.waiting) {
             return Center(
               child: CircularProgressIndicator(),
             );
-          if (snapshot.hasError)
+          }
+          if (snapshot.hasError) {
             return Center(
               child: Text("Error! please check you wifi connection"),
             );
+          }
           results = jsonDecode(snapshot.data);
           return ListView.builder(
             physics: BouncingScrollPhysics(),
             itemCount: results.length,
             itemBuilder: (context, index) {
-              var _foldingCellKey = GlobalKey<SimpleFoldingCellState>();
+              var foldingCellKey = GlobalKey<SimpleFoldingCellState>();
               return Container(
                 color: Color(0xFF2e282a),
                 alignment: Alignment.topCenter,
                 child: SimpleFoldingCell.create(
-                  key: _foldingCellKey,
+                  key: foldingCellKey,
                   frontWidget: Builder(
                     builder: (BuildContext context) {
                       return GestureDetector(

covid19_mobile_app/lib/screens/home.dart

@@ -9,6 +9,8 @@ import 'package:flutter/material.dart';
 class Home extends StatelessWidget {
   final refreshKey = GlobalKey<RefreshIndicatorState>();
 
+  Home({super.key});
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
@@ -28,8 +30,9 @@ class Home extends StatelessWidget {
               future: getAllData(),
               builder: (context, snapshot) {
                 // Display CircularProgressIndicator if data isn't fetched yet
-                if (snapshot.connectionState == ConnectionState.waiting)
+                if (snapshot.connectionState == ConnectionState.waiting) {
                   return Center(child: CircularProgressIndicator());
+                }
                 // If in case an error occurs
                 if (snapshot.hasError) {
                   return Container(

covid19_mobile_app/lib/screens/searchCountry.dart

@@ -46,12 +46,12 @@ class CountrySearchDelegate extends SearchDelegate {
       physics: BouncingScrollPhysics(),
       itemCount: suggestionsList.length,
       itemBuilder: (context, index) {
-        var _foldingCellKey = GlobalKey<SimpleFoldingCellState>();
+        var foldingCellKey = GlobalKey<SimpleFoldingCellState>();
         return Container(
           color: Color(0xFF2e282a),
           alignment: Alignment.topCenter,
           child: SimpleFoldingCell.create(
-            key: _foldingCellKey,
+            key: foldingCellKey,
             frontWidget: Builder(
               builder: (BuildContext context) {
                 return GestureDetector(
@@ -122,12 +122,12 @@ class CountrySearchDelegate extends SearchDelegate {
       physics: BouncingScrollPhysics(),
       itemCount: suggestionsList.length,
       itemBuilder: (context, index) {
-        var _foldingCellKey = GlobalKey<SimpleFoldingCellState>();
+        var foldingCellKey = GlobalKey<SimpleFoldingCellState>();
         return Container(
           color: Color(0xFF2e282a),
           alignment: Alignment.topCenter,
           child: SimpleFoldingCell.create(
-            key: _foldingCellKey,
+            key: foldingCellKey,
             frontWidget: Builder(
               builder: (BuildContext context) {
                 return GestureDetector(

covid19_mobile_app/lib/widgets/drawer.dart

@@ -3,6 +3,8 @@ import '../screens/countrylist.dart';
 import 'package:flutter/material.dart';
 
 class DrawerWidget extends StatelessWidget {
+  const DrawerWidget({super.key});
+
   @override
   Widget build(BuildContext context) {
     return Drawer(

covid19_mobile_app/lib/widgets/foldable_cell_widgets.dart

@@ -129,13 +129,13 @@ Widget buildInnerBottomWidget(String cases) {
                   context.findAncestorStateOfType<SimpleFoldingCellState>();
               foldingCellState?.toggleFold();
             },
-            child: Text(
-              "Close",
-            ),
             style: TextButton.styleFrom(
               foregroundColor: Colors.black,
               shape: StadiumBorder(),
-              overlayColor: Colors.white.withOpacity(0.5),
+              overlayColor: Colors.white.withValues(alpha: 0.5),
+            ),
+            child: Text(
+              "Close",
             ),
           ),
         ],

covid19_mobile_app/lib/widgets/info_card.dart

@@ -3,6 +3,8 @@ import 'package:flutter/material.dart';
 // this is the rounded rectangle card widget that appears on the homescreen
 Widget infoCard(BuildContext context, String title, String number) {
   return Card(
+    shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(40.0)),
+    color: Color(0xfff44e3f),
     child: Column(
       mainAxisAlignment: MainAxisAlignment.center,
       children: <Widget>[
@@ -25,7 +27,5 @@ Widget infoCard(BuildContext context, String title, String number) {
         ),
       ],
     ),
-    shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(40.0)),
-    color: Color(0xfff44e3f),
   );
 }