新增 PublishedScheduleOccurrences：发布时将周期规则按实际周次展开为只读课次明细。

明细保留课表版本、学期、来源排课条目、教学任务、场地、周次、星期和节次，并建立面向教学任务/周次、课表/场地/周次的索引。
明细在“发布课表”的同一事务内生成；发布失败不会留下半成品。

src/Jiaowu.Api/Domain/Academic/ScheduleEntities.cs

@@ -72,6 +72,23 @@ public sealed class TeachingTaskAllowedClassroom
     public Classroom? Classroom { get; set; }
 }
 
+public sealed class PublishedScheduleOccurrence : EntityBase
+{
+    public Guid SchedulePlanId { get; set; }
+    public Guid AcademicTermId { get; set; }
+    public Guid ScheduleEntryId { get; set; }
+    public Guid TeachingTaskId { get; set; }
+    public Guid? ClassroomId { get; set; }
+    public int Week { get; set; }
+    public int DayOfWeek { get; set; }
+    public int StartPeriod { get; set; }
+    public int PeriodCount { get; set; }
+    public ScheduleEntryKind Kind { get; set; }
+    public ScheduleEntry? ScheduleEntry { get; set; }
+    public TeachingTask? TeachingTask { get; set; }
+    public Classroom? Classroom { get; set; }
+}
+
 public sealed class TeachingTaskAllowedExperimentClassroom
 {
     public Guid TeachingTaskScheduleConstraintId { get; set; }