Merge branch 'phase/58-worker-card-split'

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

tests/HSchool.Server.Tests/SchoolWorkerShapeTests.cs

@@ -0,0 +1,24 @@
+using System.Reflection;
+using HSchool.Server.Game;
+
+namespace HSchool.Server.Tests;
+
+public class SchoolWorkerShapeTests
+{
+    [Fact]
+    public void SchoolWorker_IsOneInternalSealedTypeWithTheMailbox()
+    {
+        var worker = typeof(SchoolWorker);
+        Assert.True(worker.IsSealed);
+        Assert.False(worker.IsPublic);
+        Assert.Equal("SchoolWorker", worker.Name);
+
+        var mailbox = worker.GetField("_mailbox", BindingFlags.Instance | BindingFlags.NonPublic);
+        Assert.NotNull(mailbox);
+
+        var mailboxTypes = worker.Assembly.GetTypes()
+            .Where(type => type.GetField("_mailbox", BindingFlags.Instance | BindingFlags.NonPublic) is not null)
+            .ToArray();
+        Assert.Equal([typeof(SchoolWorker)], mailboxTypes);
+    }
+}