Add AI parent meetings after a class last lesson.

Class teachers rarely keep the homeroom; invited parents walk onto the map, opinions nudge, then parents leave OffCampus. No player schedule API.

src/HSchool.Content/EventDefs.cs

@@ -13,6 +13,7 @@ public static class EventTriggers
     public const string LessonStart = "lessonStart";
     public const string GenerationFailed = "generationFailed";
     public const string DirectorSummon = "directorSummon";
+    public const string ParentMeeting = "parentMeeting";
 }
 
 public static class EventActions