Dart 3.9 / Flutter 3.35 [first LLM release] (#2714)

I got carried away with Gemini and basically rewrote CI and the release
process for the new LLM reality. This work was largely completed by
Gemini.

- Bump all SDK versions to the current beta (3.9.0-0)
- Run `flutter channel beta`
- Wrote `ci_script.dart` to replace the bash scripts
- Converted repository to pub workspace #2499 
- Added llm.md and release.md
- Added redirect for deprecated Samples Index

## Pre-launch Checklist

- [x] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [x] I signed the [CLA].
- [x] I read the [Contributors Guide].
- [x] I have added sample code updates to the [changelog].
- [x] I updated/added relevant documentation (doc comments with `///`).

testing_app/integration_test/perf_test.dart

@@ -9,11 +9,13 @@ import 'package:testing_app/main.dart';
 
 void main() {
   group('Testing App Performance Tests', () {
-    final binding = IntegrationTestWidgetsFlutterBinding.ensureInitialized();
+    final binding =
+        IntegrationTestWidgetsFlutterBinding.ensureInitialized();
 
     // The fullyLive frame policy simulates
     // the way Flutter responds to animations.
-    binding.framePolicy = LiveTestWidgetsFlutterBindingFramePolicy.fullyLive;
+    binding.framePolicy =
+        LiveTestWidgetsFlutterBindingFramePolicy.fullyLive;
 
     testWidgets('Scrolling test', (tester) async {
       await tester.pumpWidget(const TestingApp());

testing_app/integration_test/state_mgmt_test.dart

@@ -12,12 +12,12 @@ import 'package:testing_app/screens/favorites.dart';
 late Favorites favoritesList;
 
 Widget createFavoritesScreen() => ChangeNotifierProvider<Favorites>(
-      create: (context) {
-        favoritesList = Favorites();
-        return favoritesList;
-      },
-      child: const MaterialApp(home: FavoritesPage()),
-    );
+  create: (context) {
+    favoritesList = Favorites();
+    return favoritesList;
+  },
+  child: const MaterialApp(home: FavoritesPage()),
+);
 
 void main() {
   group('Testing App State Management Tests', () {

testing_app/lib/screens/favorites.dart

@@ -41,7 +41,8 @@ class FavoriteItemTile extends StatelessWidget {
       padding: const EdgeInsets.all(8.0),
       child: ListTile(
         leading: CircleAvatar(
-          backgroundColor: Colors.primaries[itemNo % Colors.primaries.length],
+          backgroundColor:
+              Colors.primaries[itemNo % Colors.primaries.length],
         ),
         title: Text('Item $itemNo', key: Key('favorites_text_$itemNo')),
         trailing: IconButton(

testing_app/lib/screens/home.dart

@@ -52,7 +52,8 @@ class ItemTile extends StatelessWidget {
       padding: const EdgeInsets.all(8.0),
       child: ListTile(
         leading: CircleAvatar(
-          backgroundColor: Colors.primaries[itemNo % Colors.primaries.length],
+          backgroundColor:
+              Colors.primaries[itemNo % Colors.primaries.length],
         ),
         title: Text('Item $itemNo', key: Key('text_$itemNo')),
         trailing: IconButton(

testing_app/pubspec.yaml

@@ -1,18 +1,17 @@
 name: testing_app
 description: A sample that shows testing in Flutter.
-
 version: 1.0.0+1
+resolution: workspace
 
 environment:
-  sdk: ^3.6.0
+  sdk: ^3.9.0-0
 
 dependencies:
   flutter:
     sdk: flutter
-
   cupertino_icons: ^1.0.3
   provider: ^6.0.2
-  go_router: ">=10.0.0 <17.0.0"
+  go_router: ^16.0.0
 
 dev_dependencies:
   analysis_defaults:

testing_app/test/favorites_test.dart

@@ -11,12 +11,12 @@ import 'package:testing_app/screens/favorites.dart';
 late Favorites favoritesList;
 
 Widget createFavoritesScreen() => ChangeNotifierProvider<Favorites>(
-      create: (context) {
-        favoritesList = Favorites();
-        return favoritesList;
-      },
-      child: const MaterialApp(home: FavoritesPage()),
-    );
+  create: (context) {
+    favoritesList = Favorites();
+    return favoritesList;
+  },
+  child: const MaterialApp(home: FavoritesPage()),
+);
 
 void addItems() {
   for (var i = 0; i < 5; i++) {
@@ -52,7 +52,9 @@ void main() {
       await tester.pumpAndSettle();
 
       // Get the total number of items available.
-      final totalItems = tester.widgetList(find.byIcon(Icons.close)).length;
+      final totalItems = tester
+          .widgetList(find.byIcon(Icons.close))
+          .length;
 
       // Remove one item.
       await tester.tap(find.byIcon(Icons.close).first);

testing_app/test/home_test.dart

@@ -9,9 +9,9 @@ import 'package:testing_app/main.dart';
 import 'package:testing_app/models/favorites.dart';
 
 Widget createHomeScreen() => ChangeNotifierProvider<Favorites>(
-      create: (context) => Favorites(),
-      child: MaterialApp.router(routerConfig: router()),
-    );
+  create: (context) => Favorites(),
+  child: MaterialApp.router(routerConfig: router()),
+);
 
 void main() {
   group('Home Page Widget Tests', () {
@@ -29,7 +29,11 @@ void main() {
       expect(find.text('Item 0'), findsOneWidget);
 
       // Fling i.e scroll down.
-      await tester.fling(find.byType(ListView), const Offset(0, -200), 3000);
+      await tester.fling(
+        find.byType(ListView),
+        const Offset(0, -200),
+        3000,
+      );
       await tester.pumpAndSettle();
 
       // Check if "Item 0" disappeared.