Bun parity: support localAddress and localPort binding in net.connect

Tracks test-net-client-bind-twice from #66 and complements HTTP/2 native binding follow-up #424.\n\nAcceptance criteria:\n- parse and retain localAddress and localPort in SocketConfig\n- bind before connect through the existing socket-group ABI\n- preserve bind failure identity, including EADDRINUSE\n- emit no connect event after a failed local bind\n- cover IPv4, IPv6, and repeated-bind collision behavior on supported platforms\n- propagate the same behavior through HTTP and HTTP/2 clients\n\nParent tracker: #66

Implementation is complete locally in b1fcb36 (push queued by github.com DNS failure). SocketConfig now parses and owns localAddress/localPort, Listener forwards them, socket.doConnect preserves the local address through its NUL-terminated allocator, and SocketGroup calls the existing bun-usockets local-host/local-port ABI. The ABI and field-copy regression tests pass. This remains open until native Windows validation confirms bind conflicts and address reporting.