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

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

@@ -169,7 +169,7 @@ public sealed class PasskeyTests : IClassFixture<BackendFixture>
         Assert.Equal("no-store", login.Headers.CacheControl?.ToString());
 
         // 拿这个会话令牌就是登录状态，能力和密码登录一样
-        using var signedIn = new HttpClient { BaseAddress = _backend.BaseAddress };
+        using var signedIn = new HttpClient { BaseAddress = _backend.BaseAddress, Timeout = TimeSpan.FromSeconds(15) };
         signedIn.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", body["session_token"]!.GetValue<string>());
         JsonNode me = await JsonOf(await signedIn.GetAsync("/api/admin/auth/me"));
         Assert.Equal(_user, me["username"]!.GetValue<string>());