build(nix): add flake for development shell

[elzody]

• Target version: main

Summary

I have been using and learning Nix, and I thought some good practice would be to create a flake. The main goal right now is to be able to enter a development shell that already has the correct versions of Node, NPM, PHP, and other dependencies set up and ready to use. It is more reproducible and cleaner than using things like NVM (Node Version Manager).

TODO

• Clean up version string and package name logic
• Add Nix formatter to the flake
• Tests somehow?

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Documentation (manuals or wiki) has been updated or is not required

[provokateurin]

Cool! For Nextcloud apps it's not necessary to have their own flakes though (at least if they don't do anything special), because we have https://github.com/nextcloud/server/blob/master/flake.nix. As long as your app is located somewhere inside the server sources direnv will check recursively and automatically pick it up. You just need to make sure that the server and this repo are "in sync" regarding stable branches, so that the right versions are used.