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 `///`).

desktop_photo_search/material/lib/main.dart

@@ -24,7 +24,9 @@ void main() {
   Logger.root.level = Level.ALL;
   Logger.root.onRecord.listen((rec) {
     // ignore: avoid_print
-    print('${rec.loggerName} ${rec.level.name}: ${rec.time}: ${rec.message}');
+    print(
+      '${rec.loggerName} ${rec.level.name}: ${rec.time}: ${rec.message}',
+    );
   });
 
   if (unsplashAccessKey.isEmpty) {
@@ -39,8 +41,8 @@ void main() {
 
   runApp(
     ChangeNotifierProvider<PhotoSearchModel>(
-      create:
-          (context) => PhotoSearchModel(Unsplash(accessKey: unsplashAccessKey)),
+      create: (context) =>
+          PhotoSearchModel(Unsplash(accessKey: unsplashAccessKey)),
       child: const UnsplashSearchApp(),
     ),
   );
@@ -50,7 +52,8 @@ const double windowWidth = 1024;
 const double windowHeight = 800;
 
 void setupWindow() {
-  if (!kIsWeb && (Platform.isWindows || Platform.isLinux || Platform.isMacOS)) {
+  if (!kIsWeb &&
+      (Platform.isWindows || Platform.isLinux || Platform.isMacOS)) {
     WidgetsFlutterBinding.ensureInitialized();
     setWindowMinSize(const Size(windowWidth, windowHeight));
   }
@@ -85,9 +88,9 @@ class UnsplashHomePage extends StatelessWidget {
             onSelected: () {
               showDialog<void>(
                 context: context,
-                builder:
-                    (context) =>
-                        PhotoSearchDialog(callback: photoSearchModel.addSearch),
+                builder: (context) => PhotoSearchDialog(
+                  callback: photoSearchModel.addSearch,
+                ),
               );
             },
           ),
@@ -119,20 +122,17 @@ class UnsplashHomePage extends StatelessWidget {
     return UnsplashNotice(
       child: Scaffold(
         appBar: AppBar(title: Text(title)),
-        body:
-            photoSearchModel.entries.isNotEmpty
-                ? const UnsplashSearchContent()
-                : const Center(
-                  child: Text('Search for Photos using the Fab button'),
-                ),
-        floatingActionButton: FloatingActionButton(
-          onPressed:
-              () => showDialog<void>(
-                context: context,
-                builder:
-                    (context) =>
-                        PhotoSearchDialog(callback: photoSearchModel.addSearch),
+        body: photoSearchModel.entries.isNotEmpty
+            ? const UnsplashSearchContent()
+            : const Center(
+                child: Text('Search for Photos using the Fab button'),
               ),
+        floatingActionButton: FloatingActionButton(
+          onPressed: () => showDialog<void>(
+            context: context,
+            builder: (context) =>
+                PhotoSearchDialog(callback: photoSearchModel.addSearch),
+          ),
           tooltip: 'Search for a photo',
           child: const Icon(Icons.search),
         ),