docs: complete XML doc coverage (returns, summaries, inheritdoc)

Resolve all 622 issues flagged by the enhanced CommentChecker: add missing
<returns> tags (incl. the standard phrasing on non-generic Task methods),
add missing <summary> tags, and replace misused/redundant <inheritdoc/> on
members that override or implement nothing with real documentation.
Documentation-only — no behavior change; solution builds clean.

src/ZB.MOM.WW.ScadaBridge.StoreAndForward/NotificationForwarder.cs

@@ -35,6 +35,10 @@ public sealed class NotificationForwarder
     private readonly TimeSpan _forwardTimeout;
     private readonly ILogger<NotificationForwarder> _logger;
 
+    /// <summary>
+    /// Initializes a new <see cref="NotificationForwarder"/> that forwards buffered
+    /// notifications to the central cluster via the site communication actor.
+    /// </summary>
     /// <param name="siteCommunicationActor">
     /// The site communication actor. It forwards a <see cref="NotificationSubmit"/> to
     /// central via the registered ClusterClient and replies with the
@@ -69,6 +73,7 @@ public sealed class NotificationForwarder
     /// non-accepted ack or an Ask timeout/failure so the engine retries.
     /// </summary>
     /// <param name="message">The buffered store-and-forward message to deliver to central.</param>
+    /// <returns>A task that resolves to <c>true</c> when central accepts (or the payload is corrupt and discarded); throws on a transient forward failure so the engine retries.</returns>
     public async Task<bool> DeliverAsync(StoreAndForwardMessage message)
     {
         // StoreAndForward-018: an unreadable payload cannot be fixed by retrying.