feat(scenic): 添加水印URL配置支持

- 在ScenicConfigResp中新增watermarkUrl字段
- 在AppScenicController中设置水印URL配置项
- 支持从scenicConfig中获取watermark_url配置值

src/main/java/com/ycwl/basic/model/pc/scenic/resp/ScenicConfigResp.java

@@ -49,4 +49,5 @@ public class ScenicConfigResp {
     private Boolean enableVoucher;
     private Boolean groupingEnable;
     private Boolean showPhotoWhenWaiting;
+    private String watermarkUrl;
 }