Refuse newer save formats and add a gated dump of a live school.

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

src/HSchool.Server/Game/SchoolWorker.cs

@@ -410,6 +410,10 @@ internal sealed class SchoolWorker
                         ApplySkip(school);
                         break;
 
+                    case WorkerCommand.Dump dump:
+                        dump.Result.TrySetResult(SchoolDumpReader.Read(school, _options.SchoolWeekDays));
+                        break;
+
                     case WorkerCommand.GetPerson getPerson:
                         var card = PersonCardReader.Read(school, getPerson.PersonId, getPerson.Locale);
                         getPerson.Result.TrySetResult(
@@ -468,6 +472,9 @@ internal sealed class SchoolWorker
     {
         switch (command)
         {
+            case WorkerCommand.Dump dump:
+                dump.Result.TrySetResult(null);
+                break;
             case WorkerCommand.GetPerson getPerson:
                 getPerson.Result.TrySetResult(new PersonCardResult(null, PersonLookupError.UnknownSchool));
                 break;
@@ -493,6 +500,9 @@ internal sealed class SchoolWorker
     {
         switch (command)
         {
+            case WorkerCommand.Dump dump:
+                dump.Result.TrySetException(exception);
+                break;
             case WorkerCommand.GetPerson getPerson:
                 getPerson.Result.TrySetException(exception);
                 break;