Fix DLQ test isolation; re-include SupportsResubmission in the gate

The three DeadLetterQueue tests shared the test-commands queue and its
dead-letter sub-queue with no per-test teardown, so a message dead-lettered
by one test leaked into the next test's DLQ assertions (GUID / reason
mismatches) — environment-dependent: green in CI, red locally.

Drain the shared non-session queues (main + dead-letter) in InitializeAsync
via ReceiveAndDelete so every test starts clean. With isolation fixed all
three DLQ tests pass, so DeadLetterQueue_SupportsResubmission is no longer
excluded from the emulator gate.

Verified locally against a fresh emulator: command gate 10/10 passing
(DLQ trio included).

Author: NinjaRocks

.github/workflows/Azure-Build.yml

@@ -112,7 +112,7 @@ jobs:
         run: >-
           dotnet test tests/SourceFlow.Cloud.Azure.Tests/SourceFlow.Cloud.Azure.Tests.csproj
           --configuration Release --no-build --verbosity normal
-          --filter "FullyQualifiedName~ServiceBusCommandDispatchingTests&FullyQualifiedName!~DeadLetterQueue_SupportsResubmission&FullyQualifiedName!~SessionHandling_MultipleSessions_ProcessIndependently&FullyQualifiedName!~SessionHandling_PreservesOrderWithinSession"
+          --filter "FullyQualifiedName~ServiceBusCommandDispatchingTests&FullyQualifiedName!~SessionHandling_MultipleSessions_ProcessIndependently&FullyQualifiedName!~SessionHandling_PreservesOrderWithinSession"
           -- RunConfiguration.TestSessionTimeout=600000
 
       - name: Integration — event publishing

tests/SourceFlow.Cloud.Azure.Tests/Integration/ServiceBusCommandDispatchingTests.cs

@@ -67,6 +67,13 @@ public async Task InitializeAsync()
 
         // Create test queues
         await CreateTestQueuesAsync();
+
+        // These tests share entities on the emulator (which has no per-test
+        // teardown). Drain the shared non-session queues and their dead-letter
+        // sub-queues so each test starts from a clean state — otherwise a message
+        // dead-lettered by one test leaks into the next test's DLQ assertions.
+        await DrainQueueAsync("test-commands");
+        await DrainQueueAsync("test-commands-dedup");
     }
 
     public async Task DisposeAsync()
@@ -686,6 +693,43 @@ public async Task DeadLetterQueue_HandlesPoisonMessages()
 
     #region Helper Methods
 
+    /// <summary>
+    /// Empties a queue and its dead-letter sub-queue using ReceiveAndDelete so each
+    /// test starts from a clean state (the emulator has no admin purge endpoint).
+    /// </summary>
+    private async Task DrainQueueAsync(string queueName)
+    {
+        foreach (var subQueue in new[] { SubQueue.None, SubQueue.DeadLetter })
+        {
+            var receiver = _serviceBusClient!.CreateReceiver(queueName, new ServiceBusReceiverOptions
+            {
+                SubQueue = subQueue,
+                ReceiveMode = ServiceBusReceiveMode.ReceiveAndDelete
+            });
+
+            try
+            {
+                while (true)
+                {
+                    var messages = await receiver.ReceiveMessagesAsync(
+                        maxMessages: 100,
+                        maxWaitTime: TimeSpan.FromMilliseconds(500));
+
+                    if (messages == null || messages.Count == 0)
+                        break;
+                }
+            }
+            catch (Exception ex)
+            {
+                _output.WriteLine($"Error draining {queueName} ({subQueue}): {ex.Message}");
+            }
+            finally
+            {
+                await receiver.DisposeAsync();
+            }
+        }
+    }
+
     private async Task CreateTestQueuesAsync()
     {
         var queues = new[]