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_platform_adaptive/analysis_options.yaml

@@ -1,12 +1,7 @@
-# This file configures the analyzer, which statically analyzes Dart code to
-# check for errors, warnings, and lints.
-#
-# The issues identified by the analyzer are surfaced in the UI of Dart-enabled
-# IDEs (https://dart.dev/tools#ides-and-editors). The analyzer can also be
-# invoked from the command line by running `flutter analyze`.
+# Lint rules for Flutter apps.
+# See https://dart.dev/guides/language/analysis-options
+include: package:flutter_lints/flutter.yaml
 
-# The following line activates a set of recommended lints for Flutter apps,
-# packages, and plugins designed to encourage good coding practices.
 analyzer:
   exclude:
     - build/**
@@ -16,23 +11,13 @@ analyzer:
     - windows/**
     - macos/**
     - linux/**
-include: package:flutter_lints/flutter.yaml
 
 linter:
-  # The lint rules applied to this project can be customized in the
-  # section below to disable rules from the `package:flutter_lints/flutter.yaml`
-  # included above or to enable additional rules. A list of all available lints
-  # and their documentation is published at
-  # https://dart-lang.github.io/linter/lints/index.html.
-  #
-  # Instead of disabling a lint rule for the entire project in the
-  # section below, it can also be suppressed for a single line of code
-  # or a specific dart file by using the `// ignore: name_of_lint` and
-  # `// ignore_for_file: name_of_lint` syntax on the line or in the file
-  # producing the lint.
   rules:
-    # avoid_print: false  # Uncomment to disable the `avoid_print` rule
-    # prefer_single_quotes: true  # Uncomment to enable the `prefer_single_quotes` rule
-
-# Additional information about this file can be found at
-# https://dart.dev/guides/language/analysis-options
+    # 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_platform_adaptive/lib/main.dart

@@ -1,4 +1,3 @@
-import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'package:using_platform_adaptive/common_widgets/adaptive_button.dart';
 import 'package:using_platform_adaptive/common_widgets/adaptive_date_picker.dart';

using_platform_adaptive/macos/Flutter/GeneratedPluginRegistrant.swift

@@ -1,10 +0,0 @@
-//
-//  Generated file. Do not edit.
-//
-
-import FlutterMacOS
-import Foundation
-
-
-func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
-}

using_platform_adaptive/pubspec.yaml

@@ -20,7 +20,7 @@ publish_to: 'none' # Remove this line if you wish to publish to pub.dev
 version: 1.0.0+1
 
 environment:
-  sdk: '>=2.18.2 <3.0.0'
+  sdk: ">=3.0.0 <4.0.0"
 
 # Dependencies specify other packages that your package needs in order to work.
 # To automatically upgrade your package dependencies to the latest versions