feat(client): AddComment + comment CLI, drop Galaxy-era alarm fallback, serialize CLI tests (#598); Client.Shared off obsolete sync SDK APIs (#621)

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/IOpcUaClientService.cs

@@ -127,6 +127,16 @@ public interface IOpcUaClientService : IDisposable
     /// </returns>
     Task<StatusCode> ConfirmAlarmAsync(string conditionNodeId, byte[] eventId, string comment, CancellationToken ct = default);
 
+    /// <summary>
+    /// Attaches an operator comment to a condition (Part 9 <c>AddComment</c>) using the event identifier of an alarm notification.
+    /// </summary>
+    /// <param name="conditionNodeId">The condition node the comment is attached to.</param>
+    /// <param name="eventId">The event identifier returned by the OPC UA server for the alarm event.</param>
+    /// <param name="comment">The operator comment.</param>
+    /// <param name="ct">The cancellation token that aborts the request.</param>
+    /// <returns><see cref="StatusCodes.Good"/> on success, or the server's bad <see cref="StatusCode"/> when the call is refused.</returns>
+    Task<StatusCode> AddCommentAsync(string conditionNodeId, byte[] eventId, string comment, CancellationToken ct = default);
+
     /// <summary>
     /// Shelves or unshelves an active alarm condition (OPC UA Part 9 ShelvedStateMachine).
     /// </summary>