feat: 从系统配置读取二维码延迟显示时间，优化响应构建日志

src/main/java/com/gameplatform/server/service/link/LinkStatusService.java

@@ -888,10 +888,12 @@ private UserLinkStatusResponse doGetUserLinkStatus(Long linkId, String codeNo) {
                 response.setQrCreatedAt(now);
                 response.setQrExpireAt(qrExpireAt);
                 response.setStatus("USING");
-                response.setQrDelaySeconds(10); // 客户端收到响应后，等待5秒再请求二维码
+                // 从系统配置读取二维码延迟显示时间，默认为10秒
+                Integer qrDelaySeconds = systemConfigService.getConfigValueAsInt("link.qr_display_delay", 10);
+                response.setQrDelaySeconds(qrDelaySeconds);
                 response.setMecmachineId(selectedDeviceId); // 便于调试和维护                
-                log.info("响应构建完成: success=true, status=USING, qrCodeUrl={}, qrDelaySeconds=5, machineId={}", 
-                        qrCodeUrl, selectedDeviceId);
+                log.info("响应构建完成: success=true, status=USING, qrCodeUrl={}, qrDelaySeconds={}, machineId={}", 
+                        qrCodeUrl, qrDelaySeconds, selectedDeviceId);
                 log.info("=== 选区操作完成 ===");
 
                 return response;