WebSocket upgrades now work for WSGI apps

Minor Changes

• ee389a1: Support WebSockets for WSGI apps (e.g. Flask via flask-sock). The runtime now exposes the raw connection socket in the WSGI environ as werkzeug.socket / gunicorn.socket for WebSocket upgrade requests, and ends the request lifecycle once the 101 handshake is written so the platform can begin bidirectional streaming — matching the ASGI websocket.accept behavior.