发布课表投影改为数据库端删除旧数据、每 2,000 条分批写入并及时释放 EF 跟踪对象，避免大规模发布时内存持续增长。

为“空闲教室/预约占用”新增 学期 + 周次 + 星期 + 节次 + 场地 查询索引；新发布课表的该查询已优先走课次明细投影。

src/Jiaowu.Api/Infrastructure/Timetables/PublishedTimetableProjectionService.cs

@@ -6,6 +6,7 @@ namespace Jiaowu.Api.Infrastructure.Timetables;
 
 public sealed class PublishedTimetableProjectionService(AppDbContext db)
 {
+    private const int WriteBatchSize = 2_000;
     public async Task RebuildPublishedPlansForTaskAsync(Guid teachingTaskId, CancellationToken cancellationToken)
     {
         var plans = await db.SchedulePlans
@@ -19,10 +20,11 @@ public sealed class PublishedTimetableProjectionService(AppDbContext db)
 
     public async Task RebuildAsync(SchedulePlan plan, CancellationToken cancellationToken)
     {
-        var previous = db.PublishedScheduleOccurrences.Where(x => x.SchedulePlanId == plan.Id);
-        db.PublishedScheduleOccurrences.RemoveRange(previous);
+        await db.PublishedScheduleOccurrences
+            .Where(x => x.SchedulePlanId == plan.Id)
+            .ExecuteDeleteAsync(cancellationToken);
 
-        var rows = new List<PublishedScheduleOccurrence>();
+        var rows = new List<PublishedScheduleOccurrence>(WriteBatchSize);
         foreach (var entry in plan.Entries)
         for (var week = entry.StartWeek; week <= entry.EndWeek; week++)
         {
@@ -41,8 +43,21 @@ public sealed class PublishedTimetableProjectionService(AppDbContext db)
                 PeriodCount = entry.PeriodCount,
                 Kind = entry.Kind
             });
+            if (rows.Count == WriteBatchSize)
+                await WriteBatchAsync(rows, cancellationToken);
         }
+        if (rows.Count > 0)
+            await WriteBatchAsync(rows, cancellationToken);
+    }
+
+    private async Task WriteBatchAsync(
+        List<PublishedScheduleOccurrence> rows,
+        CancellationToken cancellationToken)
+    {
         db.PublishedScheduleOccurrences.AddRange(rows);
         await db.SaveChangesAsync(cancellationToken);
+        foreach (var row in rows)
+            db.Entry(row).State = EntityState.Detached;
+        rows.Clear();
     }
 }