feat: add a book by scanning

lib/data/repositories/book_repository.dart

@@ -1 +1,13 @@
-class BookRepository {}
+import 'package:seshat/data/services/api_client.dart';
+import 'package:seshat/domain/models/book.dart';
+import 'package:seshat/utils/result.dart';
+
+class BookRepository {
+  BookRepository({required ApiClient apiClient}) : _apiClient = apiClient;
+
+  final ApiClient _apiClient;
+
+  Future<Result<Book>> getBookByEAN(String ean) async {
+    return _apiClient.getBookByEAN(ean);
+  }
+}