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/infinite_process_page.dart

@@ -35,7 +35,9 @@ class InfiniteProcessPage extends StatelessWidget {
 
   @override
   Widget build(context) {
-    final controller = Provider.of<InfiniteProcessIsolateController>(context);
+    final controller = Provider.of<InfiniteProcessIsolateController>(
+      context,
+    );
 
     return SafeArea(
       child: Column(
@@ -196,7 +198,9 @@ class RunningList extends StatelessWidget {
 
   @override
   Widget build(context) {
-    final controller = Provider.of<InfiniteProcessIsolateController>(context);
+    final controller = Provider.of<InfiniteProcessIsolateController>(
+      context,
+    );
 
     var sums = controller.currentResults;
 
@@ -208,10 +212,9 @@ class RunningList extends StatelessWidget {
           return Column(
             children: [
               Card(
-                color:
-                    (controller.created && !controller.paused)
-                        ? Colors.lightGreenAccent
-                        : Colors.deepOrangeAccent,
+                color: (controller.created && !controller.paused)
+                    ? Colors.lightGreenAccent
+                    : Colors.deepOrangeAccent,
                 child: ListTile(
                   leading: Text('${sums.length - index}.'),
                   title: Text('${sums[index]}.'),