fix(auditlog): do not log a graceful-stop OperationCanceledException at Error in the telemetry drains (review 2026-10-21 06/COR-2)

src/ZB.MOM.WW.ScadaBridge.AuditLog/Site/Telemetry/SiteAuditTelemetryActor.cs

@@ -163,8 +163,8 @@ public class SiteAuditTelemetryActor : ReceiveActor
         // Route every async dependency call through the
         // per-actor lifecycle token so PostStop cancellation actually
         // propagates into the queue read, the gRPC push, and the
-        // mark-forwarded write. OperationCanceledException is swallowed by
-        // the catch-all below.
+        // mark-forwarded write. A shutdown-driven OperationCanceledException is
+        // swallowed silently by the dedicated catch below.
         var ct = _lifecycleCts.Token;
         try
         {
@@ -204,6 +204,12 @@ public class SiteAuditTelemetryActor : ReceiveActor
                     .ConfigureAwait(false);
             }
         }
+        catch (OperationCanceledException) when (ct.IsCancellationRequested)
+        {
+            // Graceful stop: PostStop cancelled the lifecycle token while the drain
+            // was awaiting the queue / gRPC push. Expected on every orderly shutdown or
+            // failover — not an error (review 2026-10-21 06/COR-2).
+        }
         catch (Exception ex)
         {
             // Catch-all so a SQLite hiccup or mapper bug never crashes the
@@ -382,6 +388,10 @@ public class SiteAuditTelemetryActor : ReceiveActor
                     .ConfigureAwait(false);
             }
         }
+        catch (OperationCanceledException) when (ct.IsCancellationRequested)
+        {
+            // Graceful stop mid-drain — see OnDrainAsync (review 2026-10-21 06/COR-2).
+        }
         catch (Exception ex)
         {
             _logger.LogError(ex,