“教学班成绩分析”页面新增“定时刷新设置”，支持启停、刷新间隔、单次处理上限、查看上次/下次扫描时间。

配置保存在独立数据库表 CourseGradeStatisticsRefreshSettings，不是修改 appsettings.json。
后台每 10 秒读取配置，仅到期扫描；成绩录入、导入、审批时不再立即创建统计任务。
扫描发现过期数据后，仍通过持久任务、Outbox 和 RabbitMQ 执行；Redis统计缓存由处理任务统一刷新。

src/Jiaowu.Api/Controllers/GradesController.cs

@@ -508,7 +508,6 @@ public sealed class GradesController(
         }
         targetItem.SourceType = GradeItemSourceType.ExperimentSummary;
         targetItem.SourceSnapshotAt = DateTime.UtcNow;
-        QueueCourseStatisticsRefresh(sheet.Id);
         await db.SaveChangesAsync(cancellationToken);
         return Ok(new
         {
@@ -668,7 +667,6 @@ public sealed class GradesController(
             return ConflictProblem("只有审核通过的成绩单可以发布。");
         sheet.Status = GradeSheetStatus.Published;
         sheet.PublishedAt = DateTime.UtcNow;
-        QueueCourseStatisticsRefresh(sheet.Id);
 
         // The grade sheet roster is authoritative at publication time. This also
         // covers students added through approved roster corrections.
@@ -918,7 +916,6 @@ public sealed class GradesController(
         if (errors.Count > 0)
             return ImportValidationProblem(errors);
 
-        QueueCourseStatisticsRefresh(sheet.Id);
         await db.SaveChangesAsync(cancellationToken);
         return Ok(new { updated, total = rows.Count });
     }
@@ -1161,7 +1158,6 @@ public sealed class GradesController(
     {
         try
         {
-            QueueCourseStatisticsRefresh(id);
             await db.SaveChangesAsync(cancellationToken);
             return created ? Created(string.Empty, new { id }) : NoContent();
         }
@@ -1171,14 +1167,6 @@ public sealed class GradesController(
         }
     }
 
-    private void QueueCourseStatisticsRefresh(Guid gradeSheetId)
-    {
-        var job = new CourseGradeStatisticsRefreshJob { GradeSheetId = gradeSheetId };
-        db.CourseGradeStatisticsRefreshJobs.Add(job);
-        db.BackgroundJobOutboxMessages.Add(BackgroundJobOutboxMessage.Create(
-            BackgroundJobKind.CourseGradeStatisticsRefresh, job.Id));
-    }
-
     private ActionResult ConflictProblem(string detail) =>
         Conflict(new ProblemDetails
         {