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 `///`).

simplistic_editor/lib/app_state_manager.dart

@@ -10,8 +10,8 @@ class AppStateManager extends InheritedWidget {
   }) : _appState = state;
 
   static AppStateManager of(BuildContext context) {
-    final AppStateManager? result =
-        context.dependOnInheritedWidgetOfExactType<AppStateManager>();
+    final AppStateManager? result = context
+        .dependOnInheritedWidgetOfExactType<AppStateManager>();
     assert(result != null, 'No AppStateManager found in context');
     return result!;
   }