fix(store): 修复活动状态判断逻辑

- 移除报名开始时间的备选逻辑
- 统一使用活动开始时间作为判断依据
- 简化时间逻辑处理流程

alien-job/src/main/java/shop/alien/job/store/StoreOperationalActivityJob.java

@@ -75,7 +75,7 @@ public class StoreOperationalActivityJob {
 
             // 遍历活动，判断状态
             for (StoreOperationalActivity activity : activities) {
-                Date startTime = activity.getSignupStartTime() != null ? activity.getSignupStartTime() : activity.getStartTime();
+                Date startTime = activity.getStartTime();
                 Date endTime = activity.getEndTime();
                 Integer currentStatus = activity.getStatus();