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/screens/favorites.dart

@@ -25,26 +25,32 @@ class FavoritesScreen extends StatelessWidget {
             middle: Text('My Garden'),
           ),
           child: Center(
-            child:
-                model.favoriteVeggies.isEmpty
-                    ? Padding(
-                      padding: const EdgeInsets.symmetric(horizontal: 24),
-                      child: Text(
-                        'You haven\'t added any favorite veggies to your garden yet.',
-                        style: CupertinoTheme.of(context).textTheme.textStyle,
-                      ),
-                    )
-                    : ListView(
-                      restorationId: 'list',
-                      children: [
-                        const SizedBox(height: 24),
-                        for (Veggie veggie in model.favoriteVeggies)
-                          Padding(
-                            padding: const EdgeInsets.fromLTRB(16, 0, 16, 24),
-                            child: VeggieHeadline(veggie),
-                          ),
-                      ],
+            child: model.favoriteVeggies.isEmpty
+                ? Padding(
+                    padding: const EdgeInsets.symmetric(horizontal: 24),
+                    child: Text(
+                      'You haven\'t added any favorite veggies to your garden yet.',
+                      style: CupertinoTheme.of(
+                        context,
+                      ).textTheme.textStyle,
                     ),
+                  )
+                : ListView(
+                    restorationId: 'list',
+                    children: [
+                      const SizedBox(height: 24),
+                      for (Veggie veggie in model.favoriteVeggies)
+                        Padding(
+                          padding: const EdgeInsets.fromLTRB(
+                            16,
+                            0,
+                            16,
+                            24,
+                          ),
+                          child: VeggieHeadline(veggie),
+                        ),
+                    ],
+                  ),
           ),
         );
       },