feat: add useDemoTrading flag to BaseRestClient for demo mode support

src/rest-client-v2.ts

@@ -1262,7 +1262,7 @@ export class RestClientV2 extends BaseRestClient {
   }
 
   getFuturesContractConfig(params: {
-    symbol: string;
+    symbol?: string;
     productType: FuturesProductTypeV2;
   }): Promise<APIResponse<FuturesContractConfigV2[]>> {
     return this.get('/api/v2/mix/market/contracts', params);

src/util/BaseRestClient.ts

@@ -92,6 +92,7 @@ export default abstract class BaseRestClient {
   constructor(
     restOptions: RestClientOptions = {},
     networkOptions: AxiosRequestConfig = {},
+    useDemoTrading: boolean = false,
   ) {
     this.options = {
       recvWindow: 5000,
@@ -110,6 +111,7 @@ export default abstract class BaseRestClient {
         'X-CHANNEL-API-CODE': 'hbnni',
         'Content-Type': 'application/json',
         locale: 'en-US',
+        ...(useDemoTrading ? { paptrading: '1' } : {}),
       },
     };