Inventory should support static bastion host

[Migrated]

For use cases that have a static bastion host hosted in corp network, it would be useful to have a way to specify that in the cluster.yaml file in the inventory section.

No implementation file or test is named. Start by locating how cluster.yaml and its inventory section are parsed in the CLI, then trace how bastion hosts are handled. Clarify the configuration shape and expected behavior for a static corporate-network host; done means the inventory can specify it and the workflow uses it consistently.

Written by the indexing model from the issue text.