fix(cluster): give cluster-leave phase a 15s timeout so 10s singleton drains can complete

src/ZB.MOM.WW.ScadaBridge.Host/Actors/AkkaHostedService.cs

@@ -272,6 +272,7 @@ akka {{
     }}
     coordinated-shutdown {{
         run-by-clr-shutdown-hook = on
+        phases.cluster-leave.timeout = 15s
     }}
 }}";
     }

tests/ZB.MOM.WW.ScadaBridge.Host.Tests/HoconBuilderTests.cs

@@ -26,6 +26,23 @@ public class HoconBuilderTests
         FailureDetectionThreshold = TimeSpan.FromSeconds(10),
     };
 
+    [Fact]
+    public void BuildHocon_ClusterLeavePhaseTimeout_ExceedsDrainBudget()
+    {
+        // Review 01 [Medium]: the five singleton drain tasks GracefulStop(10s)
+        // inside cluster-leave, whose default phase timeout is 5s — Akka abandons
+        // the task at 5s and the drain guarantee is silently halved.
+        var node = new NodeOptions { Role = "Central", NodeHostname = "node1", RemotingPort = 8081 };
+        var hocon = AkkaHostedService.BuildHocon(
+            node, DefaultCluster(), new[] { "Central" },
+            TimeSpan.FromSeconds(5), TimeSpan.FromSeconds(15));
+
+        var config = ConfigurationFactory.ParseString(hocon);
+        var phaseTimeout = config.GetTimeSpan("akka.coordinated-shutdown.phases.cluster-leave.timeout");
+        Assert.True(phaseTimeout >= TimeSpan.FromSeconds(15),
+            $"cluster-leave phase timeout ({phaseTimeout}) must exceed the 10s singleton GracefulStop budget");
+    }
+
     [Fact]
     public void BuildHocon_PlainValues_ParsesAndPreservesValues()
     {