[CI] [SKIP TESTS] Add detailed Probe-Agent connection diagnostics

backend/shared/MoShiro.Measurement/Core/Contracts.cs

@@ -23,6 +23,9 @@ public class DataSession
 
     public byte[] Key { get; }
 
+    /// <summary>Public node identity for diagnostics; never the data-session identifier or key.</summary>
+    public virtual string? DiagnosticPeerId => null;
+
     public IDatagramConnection? DatagramConnection => Volatile.Read(ref _datagramConnection);
 
     public void BindDatagramConnection(IDatagramConnection connection) => Volatile.Write(ref _datagramConnection, connection);