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 `///`).

compass_app/app/lib/ui/home/widgets/home_title.dart

@@ -61,12 +61,11 @@ class _Title extends StatelessWidget {
   Widget build(BuildContext context) {
     return ShaderMask(
       blendMode: BlendMode.srcIn,
-      shaderCallback:
-          (bounds) => RadialGradient(
-            center: Alignment.bottomLeft,
-            radius: 2,
-            colors: [Colors.purple.shade700, Colors.purple.shade400],
-          ).createShader(Rect.fromLTWH(0, 0, bounds.width, bounds.height)),
+      shaderCallback: (bounds) => RadialGradient(
+        center: Alignment.bottomLeft,
+        radius: 2,
+        colors: [Colors.purple.shade700, Colors.purple.shade400],
+      ).createShader(Rect.fromLTWH(0, 0, bounds.width, bounds.height)),
       child: Text(
         text,
         style: GoogleFonts.rubik(