fix: isolate Windows sample playback for NAudio 3

MeetingAssistant.Tests/HealthEndpointTests.cs

@@ -1,6 +1,7 @@
 using System.Net;
 using System.Net.Http.Json;
 using MeetingAssistant.Recording;
+using MeetingAssistant.Workflow;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Mvc.Testing;
 using Microsoft.AspNetCore.TestHost;
@@ -41,6 +42,17 @@ public sealed class HealthEndpointTests : IClassFixture<WebApplicationFactory<Pr
         Assert.Equal("ok", body?.Status);
     }
 
+    [Fact]
+    public async Task NeutralBuildReportsSpeakerPlaybackUnavailable()
+    {
+        var playback = factory.Services.GetRequiredService<IWorkflowRulesEditorSamplePlaybackQueue>();
+
+        var result = await playback.QueueAsync(1, [1, 2]);
+
+        Assert.Contains("Windows build", result);
+        Assert.DoesNotContain("Queued", result);
+    }
+
     [Fact]
     public async Task ApplicationStartupDeletesStaleTemporaryRecordings()
     {