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 `///`).

isolate_example/lib/data_transfer_page.dart

@@ -74,7 +74,9 @@ class DataTransferPage extends StatelessWidget {
                   },
                 ),
                 onPressed: () => controller.generateRandomNumbers(true),
-                child: const Text('Transfer Data with TransferableTypedData'),
+                child: const Text(
+                  'Transfer Data with TransferableTypedData',
+                ),
               ),
               ElevatedButton(
                 style: ElevatedButton.styleFrom(
@@ -207,8 +209,9 @@ class RunningList extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final progress =
-        Provider.of<DataTransferIsolateController>(context).currentProgress;
+    final progress = Provider.of<DataTransferIsolateController>(
+      context,
+    ).currentProgress;
 
     return DecoratedBox(
       decoration: BoxDecoration(color: Colors.grey[200]),