feat(promo): generate WeChat mini-program codes on create

Use getwxacodeunlimit with activity id as scene, upload PNG to OSS qrcode/, and show in HQ admin.

Co-authored-by: Cursor <cursoragent@cursor.com>

server/dukang-api/src/modules/analytics/dto/promo.dto.ts

@@ -1,4 +1,4 @@
-import { IsNotEmpty, IsOptional, IsString } from 'class-validator';
+import { IsOptional, IsString } from 'class-validator';
 
 export class PromoTouchDto {
   @IsOptional()
@@ -8,4 +8,9 @@ export class PromoTouchDto {
   @IsOptional()
   @IsString()
   qrcodeId?: string;
+
+  /** 小程序码 scene 中的推广活动 ID */
+  @IsOptional()
+  @IsString()
+  promoId?: string;
 }