Phase 3 complete: alknet-client crate implemented with: - AlknetClient struct with builder methods (with_quinn, with_tcp_tls, with_iroh, with_socks5_proxy) - ClientDialError enum with 5 variants - dial_quic, dial_tcp_tls, dial_iroh methods - SOCKS5 proxy support (Socks5ProxyConfig, Socks5Credentials, Socks5UdpSocket) - Unit tests (18) + integration test (3) - All feature combos compile and test clean - Workspace build and tests pass