`nuxi module add <module>` does not run postinstall/`nuxi prepare`

[blyedev]

This behaviour is something that tripped me up the first time i used the cli to add a module I couldn't get type completion in the config ts.

I'd assume that postinstall runs on all the installs but apparently the module add doesnt do this so i vote to automatically run nuxi prepare each time a module is added.