feature(sockets): Add the option to use unix sockets instead of a hostname / port combination

[WickedSik]

Add Unix domain socket support to the Node.js transport layer.

This allows connecting to IRC servers (or bouncers like ZNC) via Unix sockets instead of TCP host/port, which is useful when the IRC daemon runs on the same machine. Connections can be plain or TLS-wrapped.

What changed:

• src/transports/net.js — Extended the connection logic to accept a path option for Unix domain sockets. When path is provided, it takes priority over host/port. Supports both plain (net.connect) and TLS (tls.connect) modes, including client certificates and rejectUnauthorized.

• test/net.transport.test.js — Added a comprehensive test suite for the net transport. Covers plain TCP, TLS, Unix socket, and TLS-over-Unix-socket connection modes. Also covers socket lifecycle methods (close, disposeSocket, writeLine, onSocketData, etc.) and address family detection — none of which had dedicated tests before.

• README.md / docs/clientapi.md — Updated documentation with Unix socket usage examples and the new path connect option.

Usage:

client.connect({ path: '/tmp/irc.sock', nick: 'bot' });
// or with TLS
client.connect({ path: '/tmp/irc.sock', tls: true, nick: 'bot' });

When path is set, host and port are ignored. No breaking changes to existing connection behavior.