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.AuditLog/Site/Telemetry/ISiteStreamAuditClient.cs

@@ -22,6 +22,7 @@ public interface ISiteStreamAuditClient
     /// </summary>
     /// <param name="batch">The batch of audit events to forward.</param>
     /// <param name="ct">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to the ingest acknowledgement containing accepted event IDs.</returns>
     Task<IngestAck> IngestAuditEventsAsync(AuditEventBatch batch, CancellationToken ct);
 
     /// <summary>
@@ -42,5 +43,6 @@ public interface ISiteStreamAuditClient
     /// </remarks>
     /// <param name="batch">The batch of cached-call telemetry packets to forward.</param>
     /// <param name="ct">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to the ingest acknowledgement containing accepted event IDs.</returns>
     Task<IngestAck> IngestCachedTelemetryAsync(CachedTelemetryBatch batch, CancellationToken ct);
 }