auto-claude: subtask-4-2 - Create gRPC-based delivery routes provider

Add grpcDeliveryRoutesProvider to providers.dart that uses GrpcCqrsApiClient
for fetching delivery routes. Follows the same pattern as the HTTP-based
deliveryRoutesProvider: checks authentication, uses grpcClientProvider,
and handles Result<T> responses with proper error logging.

Co-Authored-By: Claude <noreply@anthropic.com>

lib/providers/providers.dart

@@ -95,6 +95,43 @@ final deliveryRoutesProvider = FutureProvider<List<DeliveryRoute>>((ref) async {
   return result.whenSuccess((routes) => routes) ?? [];
 });
 
+/// Provider for delivery routes using gRPC.
+///
+/// This is the gRPC-based alternative to [deliveryRoutesProvider].
+/// Uses [GrpcCqrsApiClient] for improved performance and type safety.
+///
+/// Example usage:
+/// ```dart
+/// final routes = ref.watch(grpcDeliveryRoutesProvider);
+/// routes.when(
+///   data: (data) => displayRoutes(data),
+///   loading: () => showLoading(),
+///   error: (error, stack) => showError(error),
+/// );
+/// ```
+final grpcDeliveryRoutesProvider = FutureProvider<List<DeliveryRoute>>((ref) async {
+  final authService = ref.watch(authServiceProvider);
+  final isAuthenticated = await authService.isAuthenticated();
+
+  if (!isAuthenticated) {
+    throw Exception('User not authenticated');
+  }
+
+  final grpcClient = ref.watch(grpcClientProvider);
+  final result = await grpcClient.getDeliveryRoutes();
+
+  return result.when(
+    success: (routes) => routes,
+    onError: (error) {
+      debugPrint('ERROR fetching delivery routes via gRPC: ${error.message}');
+      if (error.originalException != null) {
+        debugPrint('Original exception: ${error.originalException}');
+      }
+      throw Exception(error.message);
+    },
+  );
+});
+
 final deliveriesProvider = FutureProvider.family<List<Delivery>, int>((ref, routeFragmentId) async {
   final authService = ref.watch(authServiceProvider);
   final isAuthenticated = await authService.isAuthenticated();