Sorry for my deleted the response. Because I am still thinking how to reply that. I am not sure whats meaning for the 「server」word. I guess you are talking about the part 2.
As far as I have no talk about this because i think it is a scenario case.
Not everyone needs 「server」folder, It’s just a folder「name」,
You can imagine that is a middleware to connect different backend parties.
For my scenario, the server folder is a other 「Nodejs Application」 to solve the cross domain origin issue and some auth logic. Its another node application.
When jump to build the production mode of vuejs structure. Maybe you have some solution to handle this folder to support my vuejs folder structure. But It is out of these article meaning.