Add lesson attendance from presence (present/late/absent).

Co-authored-by: Cursor <cursoragent@cursor.com>

src/HSchool.Simulation/School.cs

@@ -116,6 +116,9 @@ public sealed class School : IDisposable
 
     internal DaySlot? LastDecisionSlot { get; set; }
 
+    /// <summary>Last slot <see cref="AttendanceSystem"/> observed — detects leaving a lesson to finalize absents.</summary>
+    internal DaySlot? LastAttendanceSlot { get; set; }
+
     internal Dictionary<string, DayPlan> Plans { get; } = new(StringComparer.Ordinal);
 
     internal Queue<string> DecisionQueue { get; } = new();
@@ -162,6 +165,7 @@ public sealed class School : IDisposable
         LoggedActivity.Clear();
         _lessonLogOnce.Clear();
         _lessonMarkOnce.Clear();
+        LastAttendanceSlot = null;
     }
 
     internal void AppendDayLog(PersonLogEvent row) => _dayLog.Add(row);
@@ -214,6 +218,7 @@ public sealed class School : IDisposable
         RosterSpawner.Spawn(World, roster, Catalog);
         PlanDay = null;
         LastDecisionSlot = null;
+        LastAttendanceSlot = null;
         Plans.Clear();
         DecisionQueue.Clear();
         LoggedActivity.Clear();
@@ -461,6 +466,7 @@ public sealed class School : IDisposable
             PresenceSystem.EnqueueNewlyUrgent(this, below);
             PresenceSystem.DrainDecisions(this);
             LessonLearningSystem.Apply(this, gameMinutes);
+            AttendanceSystem.Apply(this);
             peopleChanged |= ApparelWear.Apply(this, gameMinutes, Clock.Time.AddMinutes(-gameMinutes));
             peopleChanged |= AffinitySystem.Apply(this, talked);
         }