Give packs an identity so create can refuse missing deps and load in a stable order.

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

src/HSchool.Server/Game/SchoolWorker.cs

@@ -94,7 +94,7 @@ internal sealed class SchoolWorker
         _mods = mods;
         _onFailed = onFailed;
         _logger = logger;
-        _snapshot = new SchoolState(id, name, time, running, (byte)speedIndex);
+        _snapshot = new SchoolState(id, name, time, running, (byte)speedIndex, modIds ?? []);
     }
 
     public int Id => _id;
@@ -203,6 +203,7 @@ internal sealed class SchoolWorker
     private void RunLoop(CancellationToken cancellationToken)
     {
         var packIds = _mods.NormalizePackIds(_modIds);
+        _logger.LogInformation("School {SchoolId} loading packs [{Packs}].", _id, string.Join(", ", packIds));
         foreach (var packId in packIds)
         {
             if (!_mods.PackExists(packId))
@@ -577,7 +578,8 @@ internal sealed class SchoolWorker
                 school.Name,
                 school.Clock.Time,
                 school.Clock.IsRunning,
-                (byte)school.Clock.SpeedIndex));
+                (byte)school.Clock.SpeedIndex,
+                school.Catalog?.PackIds ?? _modIds ?? []));
         Volatile.Write(ref _rosterSnapshot, school.Roster);
         Volatile.Write(ref _applicantSnapshot, school.Applicants);
         Volatile.Write(ref _timetableSnapshot, school.Timetable);