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/domain/models/booking/booking.g.dart

@@ -14,10 +14,9 @@ _$BookingImpl _$$BookingImplFromJson(Map<String, dynamic> json) =>
       destination: Destination.fromJson(
         json['destination'] as Map<String, dynamic>,
       ),
-      activity:
-          (json['activity'] as List<dynamic>)
-              .map((e) => Activity.fromJson(e as Map<String, dynamic>))
-              .toList(),
+      activity: (json['activity'] as List<dynamic>)
+          .map((e) => Activity.fromJson(e as Map<String, dynamic>))
+          .toList(),
     );
 
 Map<String, dynamic> _$$BookingImplToJson(_$BookingImpl instance) =>