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

save_data_locally_with_sqlite/lib/screens/homescreen/homescreen.dart

@@ -3,6 +3,8 @@ import 'package:save_data_locally_with_sqlite/database/database_queries.dart';
 import 'package:save_data_locally_with_sqlite/screens/homescreen/widgets/note_container.dart';
 
 class HomeScreen extends StatefulWidget {
+  const HomeScreen({super.key});
+
   @override
   _HomeScreenState createState() => _HomeScreenState();
 }

save_data_locally_with_sqlite/lib/screens/homescreen/widgets/note_container.dart

@@ -1,11 +1,9 @@
 import 'package:flutter/material.dart';
-import 'package:flutter/painting.dart';
 
 class NoteContainer extends StatelessWidget {
   final String text;
   final String datetime;
-  NoteContainer({Key? key, this.text = '', this.datetime = ''})
-      : super(key: key);
+  const NoteContainer({super.key, this.text = '', this.datetime = ''});
 
   @override
   Widget build(BuildContext context) {
@@ -15,7 +13,7 @@ class NoteContainer extends StatelessWidget {
         borderRadius: BorderRadius.circular(15),
         boxShadow: [
           BoxShadow(
-            color: Colors.blue.withOpacity(.4),
+            color: Colors.blue.withValues(alpha: .4),
             spreadRadius: 2.5,
             blurRadius: 2.5,
           )
@@ -27,7 +25,7 @@ class NoteContainer extends StatelessWidget {
           Container(
             alignment: Alignment.center,
             child: Text(
-              '$datetime',
+              datetime,
               style: TextStyle(
                 color: Colors.grey.shade700,
                 fontSize: 12,
@@ -41,7 +39,7 @@ class NoteContainer extends StatelessWidget {
                 child: Container(
                   padding: EdgeInsets.symmetric(vertical: 5, horizontal: 10),
                   child: Text(
-                    '$text',
+                    text,
                   ),
                 ),
               ),