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 `///`).

veggieseasons/lib/data/app_state.dart

@@ -15,7 +15,9 @@ class AppState extends ChangeNotifier {
 
   List<Veggie> get availableVeggies {
     var currentSeason = _getSeasonForDate(DateTime.now());
-    return _veggies.where((v) => v.seasons.contains(currentSeason)).toList();
+    return _veggies
+        .where((v) => v.seasons.contains(currentSeason))
+        .toList();
   }
 
   List<Veggie> get favoriteVeggies =>
@@ -23,15 +25,16 @@ class AppState extends ChangeNotifier {
 
   List<Veggie> get unavailableVeggies {
     var currentSeason = _getSeasonForDate(DateTime.now());
-    return _veggies.where((v) => !v.seasons.contains(currentSeason)).toList();
+    return _veggies
+        .where((v) => !v.seasons.contains(currentSeason))
+        .toList();
   }
 
   Veggie getVeggie(int? id) => _veggies.singleWhere((v) => v.id == id);
 
-  List<Veggie> searchVeggies(String? terms) =>
-      _veggies
-          .where((v) => v.name.toLowerCase().contains(terms!.toLowerCase()))
-          .toList();
+  List<Veggie> searchVeggies(String? terms) => _veggies
+      .where((v) => v.name.toLowerCase().contains(terms!.toLowerCase()))
+      .toList();
 
   void setFavorite(int? id, bool isFavorite) {
     var veggie = getVeggie(id);
@@ -75,7 +78,9 @@ class AppState extends ChangeNotifier {
       case 12:
         return date.day < 22 ? Season.autumn : Season.winter;
       default:
-        throw ArgumentError('Can\'t return a season for month #${date.month}.');
+        throw ArgumentError(
+          'Can\'t return a season for month #${date.month}.',
+        );
     }
   }
 }