fix(task): 解决原位替换模式下旧映射残留问题

- 在插入新映射前先删除已存在的旧映射记录
- 添加日志记录以便追踪旧映射删除操作
- 确保轮询服务能够正确处理最新的任务渲染作业映射关系

src/main/java/com/ycwl/basic/service/task/impl/TaskTaskServiceImpl.java

@@ -722,6 +722,12 @@ public class TaskTaskServiceImpl implements TaskService {
 
                 // 写入mapping表，供轮询服务处理
                 try {
+                    // 原位替换模式下可能已有旧映射，先删除再插入
+                    TaskRenderJobMappingEntity existingMapping = taskRenderJobMappingMapper.selectByTaskId(taskId);
+                    if (existingMapping != null) {
+                        taskRenderJobMappingMapper.deleteById(existingMapping.getId());
+                        log.info("[灰度测试] 已删除旧mapping, taskId: {}, oldRenderJobId: {}", taskId, existingMapping.getRenderJobId());
+                    }
                     TaskRenderJobMappingEntity mapping = new TaskRenderJobMappingEntity();
                     mapping.setTaskId(taskId);
                     mapping.setRenderJobId(response.getJobId());