Add EventDef notices, morning and lesson bells, and info toasts.

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

tests/HSchool.Protocol.Tests/ProtocolCodecTests.cs

@@ -96,6 +96,41 @@ public class ProtocolCodecTests
         Assert.Equal(MessageType.ClientSkipEmpty, ProtocolCodec.PeekMessageType(buffer[..length]));
     }
 
+    [Fact]
+    public void DismissNotice_RoundTripsAndIsFiveBytes()
+    {
+        var message = new ClientDismissNoticeMessage(0x01020304);
+        Span<byte> buffer = stackalloc byte[ProtocolCodec.MaxFrameSize];
+
+        var length = ProtocolCodec.WriteDismissNotice(buffer, message);
+
+        Assert.Equal(5, length);
+        Assert.Equal((byte)MessageType.ClientDismissNotice, buffer[0]);
+        Assert.Equal(new byte[] { 0x04, 0x03, 0x02, 0x01 }, buffer[1..5].ToArray());
+        Assert.Equal(message, ProtocolCodec.ReadDismissNotice(buffer[..length]));
+    }
+
+    [Fact]
+    public void Notice_RoundTripsAndMatchesByteLayout()
+    {
+        var message = new ServerNoticeMessage(0x0A0B0C0D, "DayStarted", NoticeSeverity.Info, Pause: false, TtlMs: 8000, PersonId: 0);
+        var size = ProtocolCodec.NoticeSize(message);
+        Span<byte> buffer = stackalloc byte[size];
+
+        var length = ProtocolCodec.WriteNotice(buffer, message);
+
+        Assert.Equal(size, length);
+        Assert.Equal((byte)MessageType.ServerNotice, buffer[0]);
+        Assert.Equal(new byte[] { 0x0D, 0x0C, 0x0B, 0x0A }, buffer[1..5].ToArray());
+        Assert.Equal((ushort)10, System.Buffers.Binary.BinaryPrimitives.ReadUInt16LittleEndian(buffer[5..7]));
+        Assert.Equal("DayStarted"u8.ToArray(), buffer[7..17].ToArray());
+        Assert.Equal(NoticeSeverity.Info, buffer[17]);
+        Assert.Equal(0, buffer[18]);
+        Assert.Equal(8000u, System.Buffers.Binary.BinaryPrimitives.ReadUInt32LittleEndian(buffer[19..23]));
+        Assert.Equal(0u, System.Buffers.Binary.BinaryPrimitives.ReadUInt32LittleEndian(buffer[23..27]));
+        Assert.Equal(message, ProtocolCodec.ReadNotice(buffer[..length]));
+    }
+
     [Fact]
     public void Welcome_RoundTripsAndIsFourBytes()
     {