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

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

src/HSchool.Protocol/Messages.cs

@@ -84,6 +84,29 @@ public sealed record ServerMapSnapshotMessage(int SchoolId, IReadOnlyList<MapSna
 /// <summary>Jump empty nights, weekends and holidays. The server re-checks the conditions.</summary>
 public readonly record struct ClientSkipEmptyMessage;
 
+/// <summary>Closes one notice by id. Info is not stored; pausing dismiss is phase 65.</summary>
+public readonly record struct ClientDismissNoticeMessage(uint Id);
+
+/// <summary>Wire values for <see cref="ServerNoticeMessage.Severity"/>.</summary>
+public static class NoticeSeverity
+{
+    public const byte Info = 0;
+    public const byte Warning = 1;
+    public const byte Error = 2;
+}
+
+/// <summary>
+/// One school event for open clients. <paramref name="PersonId"/> is 0 when nobody is in frame.
+/// Info toasts are not replayed on OpenSchool.
+/// </summary>
+public readonly record struct ServerNoticeMessage(
+    uint Id,
+    string DefName,
+    byte Severity,
+    bool Pause,
+    uint TtlMs,
+    uint PersonId = 0);
+
 /// <summary>Where people are: 1 in a node, 2 walking through it. Off campus is omitted.</summary>
 public static class PresenceState
 {