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/itinerary_config/itinerary_config.freezed.dart

@@ -90,36 +90,30 @@ class _$ItineraryConfigCopyWithImpl<$Res, $Val extends ItineraryConfig>
   }) {
     return _then(
       _value.copyWith(
-            continent:
-                freezed == continent
-                    ? _value.continent
-                    : continent // ignore: cast_nullable_to_non_nullable
-                        as String?,
-            startDate:
-                freezed == startDate
-                    ? _value.startDate
-                    : startDate // ignore: cast_nullable_to_non_nullable
-                        as DateTime?,
-            endDate:
-                freezed == endDate
-                    ? _value.endDate
-                    : endDate // ignore: cast_nullable_to_non_nullable
-                        as DateTime?,
-            guests:
-                freezed == guests
-                    ? _value.guests
-                    : guests // ignore: cast_nullable_to_non_nullable
-                        as int?,
-            destination:
-                freezed == destination
-                    ? _value.destination
-                    : destination // ignore: cast_nullable_to_non_nullable
-                        as String?,
-            activities:
-                null == activities
-                    ? _value.activities
-                    : activities // ignore: cast_nullable_to_non_nullable
-                        as List<String>,
+            continent: freezed == continent
+                ? _value.continent
+                : continent // ignore: cast_nullable_to_non_nullable
+                      as String?,
+            startDate: freezed == startDate
+                ? _value.startDate
+                : startDate // ignore: cast_nullable_to_non_nullable
+                      as DateTime?,
+            endDate: freezed == endDate
+                ? _value.endDate
+                : endDate // ignore: cast_nullable_to_non_nullable
+                      as DateTime?,
+            guests: freezed == guests
+                ? _value.guests
+                : guests // ignore: cast_nullable_to_non_nullable
+                      as int?,
+            destination: freezed == destination
+                ? _value.destination
+                : destination // ignore: cast_nullable_to_non_nullable
+                      as String?,
+            activities: null == activities
+                ? _value.activities
+                : activities // ignore: cast_nullable_to_non_nullable
+                      as List<String>,
           )
           as $Val,
     );
@@ -168,36 +162,30 @@ class __$$ItineraryConfigImplCopyWithImpl<$Res>
   }) {
     return _then(
       _$ItineraryConfigImpl(
-        continent:
-            freezed == continent
-                ? _value.continent
-                : continent // ignore: cast_nullable_to_non_nullable
-                    as String?,
-        startDate:
-            freezed == startDate
-                ? _value.startDate
-                : startDate // ignore: cast_nullable_to_non_nullable
-                    as DateTime?,
-        endDate:
-            freezed == endDate
-                ? _value.endDate
-                : endDate // ignore: cast_nullable_to_non_nullable
-                    as DateTime?,
-        guests:
-            freezed == guests
-                ? _value.guests
-                : guests // ignore: cast_nullable_to_non_nullable
-                    as int?,
-        destination:
-            freezed == destination
-                ? _value.destination
-                : destination // ignore: cast_nullable_to_non_nullable
-                    as String?,
-        activities:
-            null == activities
-                ? _value._activities
-                : activities // ignore: cast_nullable_to_non_nullable
-                    as List<String>,
+        continent: freezed == continent
+            ? _value.continent
+            : continent // ignore: cast_nullable_to_non_nullable
+                  as String?,
+        startDate: freezed == startDate
+            ? _value.startDate
+            : startDate // ignore: cast_nullable_to_non_nullable
+                  as DateTime?,
+        endDate: freezed == endDate
+            ? _value.endDate
+            : endDate // ignore: cast_nullable_to_non_nullable
+                  as DateTime?,
+        guests: freezed == guests
+            ? _value.guests
+            : guests // ignore: cast_nullable_to_non_nullable
+                  as int?,
+        destination: freezed == destination
+            ? _value.destination
+            : destination // ignore: cast_nullable_to_non_nullable
+                  as String?,
+        activities: null == activities
+            ? _value._activities
+            : activities // ignore: cast_nullable_to_non_nullable
+                  as List<String>,
       ),
     );
   }

compass_app/app/lib/domain/models/itinerary_config/itinerary_config.g.dart

@@ -10,14 +10,12 @@ _$ItineraryConfigImpl _$$ItineraryConfigImplFromJson(
   Map<String, dynamic> json,
 ) => _$ItineraryConfigImpl(
   continent: json['continent'] as String?,
-  startDate:
-      json['startDate'] == null
-          ? null
-          : DateTime.parse(json['startDate'] as String),
-  endDate:
-      json['endDate'] == null
-          ? null
-          : DateTime.parse(json['endDate'] as String),
+  startDate: json['startDate'] == null
+      ? null
+      : DateTime.parse(json['startDate'] as String),
+  endDate: json['endDate'] == null
+      ? null
+      : DateTime.parse(json['endDate'] as String),
   guests: (json['guests'] as num?)?.toInt(),
   destination: json['destination'] as String?,
   activities: