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/booking/view_models/booking_viewmodel.dart

@@ -50,8 +50,8 @@ class BookingViewModel extends ChangeNotifier {
 
   Future<Result<void>> _createBooking() async {
     _log.fine('Loading booking');
-    final itineraryConfig =
-        await _itineraryConfigRepository.getItineraryConfig();
+    final itineraryConfig = await _itineraryConfigRepository
+        .getItineraryConfig();
     switch (itineraryConfig) {
       case Ok<ItineraryConfig>():
         _log.fine('Loaded stored ItineraryConfig');