Add support for the shell Nushell

[TechWatching]

I'm using the shell Nushell as my main shell, I would love to have support for it when using spec kit.

Many tools nowadays have support for Nushell which is a popular cross-platform shell (36.5k stars on GitHub). I think it would be interesting for others as well.

From my understanding, the main thing to do is to add a new folder in scripts with the corresponding scripts for Nushell. Adn then add the option for Nushell in src/specify_cli/init.py

Would you accept contributions for it?

[localden]

@TechWatching in Nushell, are you still running Bash scripts or something else entirely?

[TechWatching]

Something else entirely. You develop shell scripts in nu. It's not a POSIX compatible shell.

[localden]

Transparently, my biggest concern here would be maintenance - even with maintaining both shell and PowerShell scripts today it's a hassle because if there's a bug in one script, I have to now run through all others and spot the issues. Coupled with the fact that we don't have Nushell experts on staff AFAIK, this means that the scripts would essentially be unmaintainable short of either:

1. Using AI to try and fix things. This can work to a degree, but I am not confident that this will always work well.
2. Lean on the community to fix things, which doesn't scale for a large project.

[TechWatching]

Transparently, my biggest concern here would be maintenance - even with maintaining both shell and PowerShell scripts today it's a hassle because if there's a bug in one script, I have to now run through all others and spot the issues. Coupled with the fact that we don't have Nushell experts on staff AFAIK, this means that the scripts would essentially be unmaintainable short of either:

1. Using AI to try and fix things. This can work to a degree, but I am not confident that this will always work well.
2. Lean on the community to fix things, which doesn't scale for a large project.

I understand, yet that's the best moment to ask to add support with the project still at its beginning phase.

If support is not built-in because of what you mentioned, do you think the support could be provided by the community through a plugin system? Obviously forking the repository just to add support for nushell will never be maintainable, but if there were a kind a plugin system, that could be something doable I guess.