chore(h3): add TODO for EarlyData 0-RTT transport wiring

Author: st0o0

src/TurboHTTP/Protocol/Http3/Http3Frame.cs

@@ -129,6 +129,7 @@ internal sealed class Http3HeadersFrame : Http3Frame, IDisposable
     /// The transport layer uses this flag to decide whether to send the request
     /// before the TLS handshake completes. RFC 9114 §A.1.
     /// </summary>
+    // TODO: Not yet wired to transport layer — requires QUIC 0-RTT stream coordination
     public bool EarlyData { get; set; }
 
     public Http3HeadersFrame(ReadOnlyMemory<byte> headerBlock)

src/TurboHTTP/Protocol/Http3/StateMachine.cs

@@ -527,6 +527,7 @@ private IReadOnlyList<Http3Frame> EncodeToFrames(HttpRequestMessage request)
         OriginValidator.Validate(request.RequestUri!, request.Method == HttpMethod.Connect);
         var frames = _requestEncoder.Encode(request);
 
+        // TODO: EarlyData flag is set but not yet consumed by transport layer
         if (_options.Http3.AllowEarlyData && IdempotentMethods.Contains(request.Method))
         {
             foreach (var f in frames)