Update reviewed phase details, enhance presence tests for hiring and assigning teachers during lessons, and fix timetable handling in the School class. Added new tests for presence management and ensured proper campus staffing behavior during lesson transitions.

src/HSchool.Simulation/School.cs

@@ -231,6 +231,10 @@ public sealed class School : IDisposable
         ArgumentNullException.ThrowIfNull(timetable);
         Timetable = timetable;
         TimetableDirty = false;
+        // Duty rooms and AppearAt come from this table. EnsurePlans only rebuilds when the day
+        // or the roster size changes, so a pin or an assign would otherwise keep yesterday's
+        // empty-staff plans and leave the campus empty.
+        PlanDay = null;
         LastDecisionSlot = null;
         foreach (var id in Roster?.People.Select(person => person.Id) ?? [])
         {