[compass_app] Standardize on Result factories rather than constructors (#2538)

From my review of the recipes PR in
https://github.com/flutter/website/pull/11444#pullrequestreview-2480423811.

compass_app/app/lib/data/repositories/auth/auth_repository_dev.dart

@@ -16,12 +16,12 @@ class AuthRepositoryDev extends AuthRepository {
     required String email,
     required String password,
   }) async {
-    return Result.ok(null);
+    return const Result.ok(null);
   }
 
   /// Logout is always successful in dev scenarios
   @override
   Future<Result<void>> logout() async {
-    return Result.ok(null);
+    return const Result.ok(null);
   }
 }

compass_app/app/lib/data/repositories/booking/booking_repository_local.dart

@@ -31,7 +31,7 @@ class BookingRepositoryLocal implements BookingRepository {
     // Bookings created come without id, we need to assign one
     final bookingWithId = booking.copyWith(id: _sequentialId++);
     _bookings.add(bookingWithId);
-    return Result.ok(null);
+    return const Result.ok(null);
   }
 
   @override
@@ -92,6 +92,6 @@ class BookingRepositoryLocal implements BookingRepository {
   @override
   Future<Result<void>> delete(int id) async {
     _bookings.removeWhere((booking) => booking.id == id);
-    return Result.ok(null);
+    return const Result.ok(null);
   }
 }

compass_app/app/lib/data/repositories/itinerary_config/itinerary_config_repository_memory.dart

@@ -22,6 +22,6 @@ class ItineraryConfigRepositoryMemory implements ItineraryConfigRepository {
     ItineraryConfig itineraryConfig,
   ) async {
     _itineraryConfig = itineraryConfig;
-    return Result.ok(true);
+    return const Result.ok(true);
   }
 }