docs(xmldoc): fill missing XML docs + strip tracking-ID comments across src

Adds <summary>/<param>/<returns>/<inheritdoc> where missing and removes
project bookkeeping IDs (task/tracking refs) from shipped code comments,
so the docs read cleanly and CommentChecker is quiet except for known
false positives (PLC/protocol terms, event/IEqualityComparer inheritdoc).
Doc/comment-only; no logic changed; solution builds clean.

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Interfaces/IFleetDiagnosticsClient.cs

@@ -11,5 +11,6 @@ public interface IFleetDiagnosticsClient
     /// <summary>Gets diagnostics for the specified node.</summary>
     /// <param name="nodeId">The node ID to retrieve diagnostics for.</param>
     /// <param name="ct">The cancellation token.</param>
+    /// <returns>The diagnostics snapshot for the requested node.</returns>
     Task<NodeDiagnosticsSnapshot> GetDiagnosticsAsync(NodeId nodeId, CancellationToken ct);
 }