Host node awareness

**Describe the feature**
NTH v2 should be aware of which node it's running on so that it can optimise the workflow for cordon/drain of that node, ideally so it exits cleanly.

**Is the feature request related to a problem?**
NTH will terminate itself leaving errors in the logs.

**Describe alternatives you've considered**
n/a

未指定任何文件、测试或入口点。首先跟踪 NTH v2 节点终止工作流，尤其是 cordon/drain 的处理，并确定主机节点感知应如何支持干净退出；完成的标准是 handler 在自身节点上终止时不会留下错误。

由索引模型根据 Issue 内容生成。