修复结训：锁定参训记录避免结训并发竞态

RuoYi-Vue/ruoyi-train/src/main/java/com/ruoyi/train/service/impl/EnrollmentPlanCompletionAdapter.java

@@ -41,6 +41,10 @@ public class EnrollmentPlanCompletionAdapter implements PlanEnrollmentCompletion
     @Override
     public void precheckCompletion(String planId)
     {
+        // 按 enrollment_id 稳定升序锁定该计划下全部学员记录 (SELECT ... ORDER BY enrollment_id FOR UPDATE)，
+        // 阻止结训与学员报到/状态修改之间的并发竞态与 TOCTOU 窗口
+        trainEnrollmentService.selectEnrollmentsForUpdateByPlanId(planId);
+
         List<java.util.Map<String, Object>> stats = trainEnrollmentService.selectEnrollmentCompletionStatsByPlanId(planId);
         int status0Waiting = 0;
         int status1Reported = 0;