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

using_firebase_db/.flutter-plugins-dependencies

@@ -1 +0,0 @@
-{"info":"This is a generated file; do not edit or check into version control.","plugins":{"ios":[{"name":"firebase_core","path":"/Users/nishantsrivastava/.pub-cache/hosted/pub.dev/firebase_core-4.13.0/","native_build":true,"dependencies":[],"dev_dependency":false},{"name":"firebase_database","path":"/Users/nishantsrivastava/.pub-cache/hosted/pub.dev/firebase_database-12.4.7/","native_build":true,"dependencies":["firebase_core"],"dev_dependency":false}],"android":[{"name":"firebase_core","path":"/Users/nishantsrivastava/.pub-cache/hosted/pub.dev/firebase_core-4.13.0/","native_build":true,"dependencies":[],"dev_dependency":false},{"name":"firebase_database","path":"/Users/nishantsrivastava/.pub-cache/hosted/pub.dev/firebase_database-12.4.7/","native_build":true,"dependencies":["firebase_core"],"dev_dependency":false}],"macos":[{"name":"firebase_core","path":"/Users/nishantsrivastava/.pub-cache/hosted/pub.dev/firebase_core-4.13.0/","native_build":true,"dependencies":[],"dev_dependency":false},{"name":"firebase_database","path":"/Users/nishantsrivastava/.pub-cache/hosted/pub.dev/firebase_database-12.4.7/","native_build":true,"dependencies":["firebase_core"],"dev_dependency":false}],"linux":[],"windows":[{"name":"firebase_core","path":"/Users/nishantsrivastava/.pub-cache/hosted/pub.dev/firebase_core-4.13.0/","native_build":true,"dependencies":[],"dev_dependency":false},{"name":"firebase_database","path":"/Users/nishantsrivastava/.pub-cache/hosted/pub.dev/firebase_database-12.4.7/","native_build":true,"dependencies":["firebase_core"],"dev_dependency":false}],"web":[{"name":"firebase_core_web","path":"/Users/nishantsrivastava/.pub-cache/hosted/pub.dev/firebase_core_web-3.10.0/","dependencies":[],"dev_dependency":false},{"name":"firebase_database_web","path":"/Users/nishantsrivastava/.pub-cache/hosted/pub.dev/firebase_database_web-0.2.7+13/","dependencies":["firebase_core_web"],"dev_dependency":false}]},"dependencyGraph":[{"name":"firebase_core","dependencies":["firebase_core_web"]},{"name":"firebase_core_web","dependencies":[]},{"name":"firebase_database","dependencies":["firebase_core","firebase_database_web"]},{"name":"firebase_database_web","dependencies":["firebase_core","firebase_core_web"]}],"date_created":"2026-08-16 19:49:25.655397","version":"3.47.0","swift_package_manager_enabled":{"ios":false,"macos":false}}

using_firebase_db/analysis_options.yaml

@@ -0,0 +1,23 @@
+# Lint rules for Flutter apps.
+# See https://dart.dev/guides/language/analysis-options
+include: package:flutter_lints/flutter.yaml
+
+analyzer:
+  exclude:
+    - build/**
+    - android/**
+    - ios/**
+    - web/**
+    - windows/**
+    - macos/**
+    - linux/**
+
+linter:
+  rules:
+    # Noise in small sample apps; keep the code readable.
+    avoid_print: false
+    avoid_unnecessary_containers: false
+    file_names: false
+    library_private_types_in_public_api: false
+    non_constant_identifier_names: false
+    strict_top_level_inference: false

using_firebase_db/android/app/src/main/AndroidManifest.xml

@@ -12,6 +12,7 @@
         android:icon="@mipmap/ic_launcher">
         <activity
             android:name="io.flutter.embedding.android.FlutterActivity"
+            android:exported="true"
             android:launchMode="singleTop"
             android:theme="@style/LaunchTheme"
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"

using_firebase_db/lib/main.dart

@@ -16,6 +16,8 @@ class Note {
 void main() => runApp(MyApp());
 
 class MyApp extends StatelessWidget {
+  const MyApp({super.key});
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
@@ -29,7 +31,7 @@ class MyApp extends StatelessWidget {
 }
 
 class MyHomePage extends StatefulWidget {
-  MyHomePage({super.key, required this.title});
+  const MyHomePage({super.key, required this.title});
 
   final String title;
   @override
@@ -74,6 +76,12 @@ class _MyHomePageState extends State<MyHomePage> {
     });
   }
 
+  @override
+  void dispose() {
+    _noteAddedStream.cancel();
+    super.dispose();
+  }
+
   // The note has to be cleared from the database and the local list
   void _deleteNote(int position) {
     String id = items[position].id;
@@ -97,8 +105,8 @@ class _MyHomePageState extends State<MyHomePage> {
             Container(
               padding: EdgeInsets.all(15.0),
               child: TextField(
-                style: new TextStyle(
-                    fontSize: 24.0, height: 2.0, color: Colors.black),
+                style:
+                    TextStyle(fontSize: 24.0, height: 2.0, color: Colors.black),
                 decoration: InputDecoration(
                     border: InputBorder.none, hintText: 'Add a note'),
                 controller: inputController,

using_firebase_db/pubspec.yaml

@@ -28,6 +28,7 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
+  flutter_lints: ^6.0.0
 
 
 # For information on the generic Dart part of this file, see the