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

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

src/HSchool.Content/PeopleDefValidator.cs

@@ -722,6 +722,17 @@ internal static class PeopleDefValidator
                 previous = floor;
             }
         }
+
+        if (behavior.AttendanceMax < 0)
+        {
+            throw new ContentLoadException($"BehaviorDef '{behavior.DefName}' attendanceMax cannot be negative.");
+        }
+
+        if (behavior.LessonLateMinutes < 0f)
+        {
+            throw new ContentLoadException(
+                $"BehaviorDef '{behavior.DefName}' lessonLateMinutes cannot be negative.");
+        }
     }
 
     private static void ValidateTopic(TopicDef topic, DefCatalog catalog)

src/HSchool.Content/PeopleDefs.cs

@@ -619,6 +619,23 @@ public sealed class BehaviorDef : Def
     /// </summary>
     public int? LessonMarkWhenNoTeacher { get; init; } = 2;
 
+    /// <summary>
+    /// How many recent attendance rows a person keeps. Oldest drop first. Zero disables attendance.
+    /// </summary>
+    public int AttendanceMax { get; init; } = 40;
+
+    /// <summary>
+    /// Minutes after the bell: first standing in the room within this window is present;
+    /// later is late. Inclusive — arrival at exactly this many minutes still counts as present.
+    /// </summary>
+    public float LessonLateMinutes { get; init; } = 5f;
+
+    /// <summary>
+    /// When true (vanilla), a late arrival still receives a lesson mark if they are standing in
+    /// the room — stage A quality path. False skips the mark for late pupils.
+    /// </summary>
+    public bool LessonMarkWhenLate { get; init; } = true;
+
     public static IReadOnlyList<float> DefaultLessonMarkThresholds { get; } =
     [
         0.85f,