Improve gateway reliability and dashboard docs

src/MxGateway.Worker/MxAccess/MxAccessStaSession.cs

@@ -127,6 +127,16 @@ public sealed class MxAccessStaSession : IWorkerRuntimeSession
         return eventQueue.Drain(maxEvents);
     }
 
+    public WorkerFault? DrainFault()
+    {
+        return eventQueue.DrainFault();
+    }
+
+    public bool CancelCommand(string correlationId)
+    {
+        return commandDispatcher?.CancelQueuedCommand(correlationId) ?? false;
+    }
+
     public Task<IReadOnlyList<RegisteredServerHandle>> GetRegisteredServerHandlesAsync(
         CancellationToken cancellationToken = default)
     {
@@ -207,7 +217,14 @@ public sealed class MxAccessStaSession : IWorkerRuntimeSession
                 throw new TimeoutException($"MXAccess graceful shutdown exceeded {timeout}.");
             }
 
-            result = await cleanupTask.ConfigureAwait(false);
+            try
+            {
+                result = await cleanupTask.ConfigureAwait(false);
+            }
+            catch (OperationCanceledException) when (!cancellationToken.IsCancellationRequested)
+            {
+                throw new TimeoutException($"MXAccess graceful shutdown exceeded {timeout}.");
+            }
         }
 
         TimeSpan remaining = timeout - stopwatch.Elapsed;
@@ -232,7 +249,17 @@ public sealed class MxAccessStaSession : IWorkerRuntimeSession
 
         if (session is not null)
         {
-            staRuntime.InvokeAsync(() => session.Dispose()).GetAwaiter().GetResult();
+            try
+            {
+                staRuntime.InvokeAsync(() => session.Dispose())
+                    .Wait(TimeSpan.FromSeconds(2));
+            }
+            catch (AggregateException)
+            {
+            }
+            catch (ObjectDisposedException)
+            {
+            }
         }
 
         staRuntime.Dispose();