-spec socket_addr_opts(map()) -> [inet6 | {ip, inet:ip_address()}].

Build inet listen options from the ip'/inet6' keys of a listen-opts map.

An IPv6 ip' tuple (an 8-tuple) orinet6 => true' selects the inet6' family;ip' sets the bind address. Returns a list suitable for the gen_tcp'/ssl' listen options or quic's extra_socket_opts'. Returns[]' when neither key is set, so callers fall back to default binding.