feat(service): 实现 MemberCouponService 的 obj 方法

src/main/java/com/xynet/marketing/service/impl/MemberCouponServiceImpl.java

@@ -126,7 +126,10 @@ public class MemberCouponServiceImpl extends ServiceImpl<MemberCouponMapper, Mem
 
     @Override
     public Map<String, Object> obj(JMap<String, Object> param) {
-        return null;
+        LambdaQueryWrapper<MemberCoupon> lqw = commonQueryWrapper(param).last("limit 1");
+        MemberCoupon obj = getOne(lqw);
+        Map<String, Object> vo = JHashMap.copy(obj);
+        return vo;
     }
 
     @Override