perf(tests): isolate network E2E and await QUIC cleanup

backend/tests/MoShiro.Backend.Tests/AgentHarness.cs

@@ -46,7 +46,7 @@ public sealed class AgentHarness : IAsyncDisposable
     {
         string directory = Path.Combine(Path.GetTempPath(), "moshiro-agent-" + Guid.NewGuid().ToString("N"));
         string token = pin?.Code ?? await backend.CreateJoinTokenAsync();
-        using var http = new HttpClient();
+        using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(15) };
         Result<EnrollmentResult> enrolled = await EnrollmentClient.EnrollAsync(
             http, backend.BaseAddress, token, name ?? backend.UniqueName("agent"), directory, AgentApp.Version, null, TimeProvider.System, CancellationToken.None, pin?.Genesis, pin?.Controllers);
         Assert.True(enrolled.IsSuccess, enrolled.IsSuccess ? "" : enrolled.Error.ToString());
@@ -62,7 +62,7 @@ public sealed class AgentHarness : IAsyncDisposable
         };
         configure?.Invoke(config);
         LoadedNodeIdentity identity = LoadedNodeIdentity.Load(directory);
-        var app = new AgentApp(config, identity, directory, TimeProvider.System, new ConsoleNodeLog(TimeProvider.System, Console.Out));
+        var app = new AgentApp(config, identity, directory, TimeProvider.System, NullNodeLog.Instance);
         var harness = new AgentHarness(backend, directory, identity, app);
         await app.Ready.WaitAsync(TimeSpan.FromSeconds(10));
         await BackendFixture.EventuallyAsync(() => Task.FromResult(app.Link.IsConnected), because: "the agent should connect to the backend");
@@ -137,7 +137,7 @@ public sealed class AgentHarness : IAsyncDisposable
             // 停止中
         }
 
-        App.Dispose();
+        await App.DisposeAsync();
         _identity.Dispose();
         _stop.Dispose();
         try