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/server/lib/model/booking/booking.g.dart

@@ -13,10 +13,9 @@ _$BookingImpl _$$BookingImplFromJson(Map<String, dynamic> json) =>
       endDate: DateTime.parse(json['endDate'] as String),
       name: json['name'] as String,
       destinationRef: json['destinationRef'] as String,
-      activitiesRef:
-          (json['activitiesRef'] as List<dynamic>)
-              .map((e) => e as String)
-              .toList(),
+      activitiesRef: (json['activitiesRef'] as List<dynamic>)
+          .map((e) => e as String)
+          .toList(),
     );
 
 Map<String, dynamic> _$$BookingImplToJson(_$BookingImpl instance) =>