Bump protocol to v9 and carry talk-circle ids on the presence frame.

Names stay off the wire; a person not in a circle writes an empty member list and topic.

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

src/HSchool.Protocol/Messages.cs

@@ -98,8 +98,22 @@ public sealed record PresenceNode(
     string ActivitySubject = "",
     string ActivityClass = "");
 
-/// <summary>One on-campus person. Names are resolved over HTTP, not on this frame.</summary>
-public sealed record PresencePerson(string Id, string NodeId, byte State);
+/// <summary>
+/// One on-campus person. Names are resolved over HTTP, not on this frame. Talk members and
+/// topic are ids; an empty list means the person is not in a circle.
+/// </summary>
+public sealed record PresencePerson(
+    string Id,
+    string NodeId,
+    byte State,
+    IReadOnlyList<string> TalkMemberIds,
+    string TalkTopicId)
+{
+    public PresencePerson(string id, string nodeId, byte state)
+        : this(id, nodeId, state, [], "")
+    {
+    }
+}
 
 /// <summary>
 /// Live occupancy of an open school, about twice a second. Counts and people cover the whole