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/pubspec.yaml

@@ -1,5 +1,7 @@
 name: simplistic_editor
 description: A new Flutter project.
+version: 1.0.0+1
+resolution: workspace
 
 # The following line prevents the package from being accidentally published to
 # pub.dev using `flutter pub publish`. This is preferred for private packages.
@@ -15,10 +17,10 @@ publish_to: 'none' # Remove this line if you wish to publish to pub.dev
 # In iOS, build-name is used as CFBundleShortVersionString while build-number used as CFBundleVersion.
 # Read more about iOS versioning at
 # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
-version: 1.0.0+1
+
 
 environment:
-  sdk: ^3.7.0-0
+  sdk: ^3.9.0-0
 
 # Dependencies specify other packages that your package needs in order to work.
 # To automatically upgrade your package dependencies to the latest versions
@@ -30,7 +32,6 @@ dependencies:
   flutter:
     sdk: flutter
 
-
   # The following adds the Cupertino Icons font to your application.
   # Use with the CupertinoIcons class for iOS style icons.
   cupertino_icons: ^1.0.2
@@ -40,7 +41,6 @@ dev_dependencies:
     path: ../analysis_defaults
   flutter_test:
     sdk: flutter
-
 # For information on the generic Dart part of this file, see the
 # following page: https://dart.dev/tools/pub/pubspec