feat(add): init Guided provider setup

[joshnuss]

Adds a command called add to provide a guided setup for auth providers.

Requirements

1. If [provider] is invalid or not provider, ask "What provider do you want to set up?"
2. what's the hostname (default could be to detect the frameworks default localhost:port, + the basepath for the redirect url, eg. /api/auth for NextAuth.js, and /auth for all others)
3. show the OAuth Registration URL (or maybe even open in the browser automatically?)
4. copy the callback url to the clipboard and ask the user to paste it into the OAuth registration form
5. ask for pasting the client id
6. ask for pasting the client secret
7. write to the framework's preferred .env
8. inform to add the provider import in the correct file. (we can make it automatic in a follow-up PR)

☕️ Reasoning

Setting up providers can be a jarring experience, because all UIs and instructions are different. It would be nice to have a guided setup to reduce friction.

🧢 Checklist

• Documentation
• Tests
• Ready to be merged

🎫 Affected issues

None

📌 Resources

• Security guidelines
• Contributing guidelines
• Code of conduct
• Contributing to Open Source

[joshnuss]

Notes

1. Currently supporting Google, Apple, and GitHub
2. It's not yet printing out code instructions, ie "add an import, update providers:"
3. I've added a requireFramework() function that bails if the framework cannot be determined. Since auth secret was doing the same thing, figured logic could be shared.
4. Clipboard code is not working on my machine (Linux Mint). The command ends up erroring. I debugged it and found it was using this command:

$> DISPLAY=:0 LC_CTYPE=UTF-8 /bin/xclip -i "http:/localhost:5173/auth/callbacks/google"
/bin/xclip: http:/localhost:5173/auth/callbacks/google: No such file or directory

Questions

• Should non-oauth setups be supported too? For example, passwords, passwordless, sso/saml
• Should there be tests?
• Should instructions be in lib/meta.js? Right now providers is a mapping of key -> string, but we could change it to map to object that has the "instructions" data & name.
• Should env vars be written to top of file or bottom (right now, it's placed at the top)

[joshnuss]

@balazsorban44 Is this imported anywhere?