Write integration tests for the AG-UI .NET SDK. USE FOR: adding a new AG-UI event type and covering it end-to-end, testing SSE or protobuf streaming through the hosting pipeline, verifying AGUIChatClient maps events to ChatResponseUpdate, multi-turn conversation tests, parameterizing a test over Json/Protobuf transports, adding or updating a GettingStarted sample replay/Verify snapshot. Covers: WebApplicationFactory + DelegatingStreamingChatClient setup, IChatClient-based assertions with Assert.Collection, TransportFormat [Theory] (Json/Protobuf), recording/replay capture infrastructure, and the 8-capture-point Verify baselines. DO NOT USE FOR: unit tests of event serialization (use tests/AGUI.Abstractions.UnitTests) or stream-conversion unit tests (use tests/AGUI.Server.UnitTests).