create promocode page

lib/data/network/api_service.dart

@@ -1150,4 +1150,31 @@ class ApiService {
     }
     return null;
   }
+
+  Future<Map<String, dynamic>> applyPromoCode(String code) async {
+    final token = await _securityService.getAccessToken();
+    if (token == null) throw Exception('No access token');
+
+    final response = await _dio.post(
+      '$baseUrl/promocode/apply',
+      data: {'code': code},
+      options: Options(
+        headers: {
+          'Content-Type': 'application/json',
+          'Authorization': 'Bearer $token',
+        },
+      ),
+    );
+
+    if (response.statusCode == 201 || response.statusCode == 200) {
+      return response.data;
+    } else if (response.statusCode == 404) {
+      throw PromoCodeNotFoundException();
+    } else {
+      throw Exception('API Error: ${response.statusCode}');
+    }
+  }
 }
+
+// ✅ Добавь исключение (можно в отдельный файл)
+class PromoCodeNotFoundException implements Exception {}