Otter 机器添加 IP 校验检查允许 Hostname

在添加机器配置的时候请允许使用 `hostname` 进行配置，因为在 DEMO 环境下面利用 `hostname` 会避免 VLAN 中 `IP` 自动分配等问题。

Start at the machine-configuration entry point and locate the IP validation performed when adding a machine. Confirm how DEMO configurations are validated, then make the completion condition explicit: hostname values should be accepted while existing IP configurations continue to work. No file or test is named in the issue, so identify the relevant validation tests before changing behavior.

Written by the indexing model from the issue text.