Summary

This adds a flake.nix to our repo for building and distributing Devbox. This will make it easier for developers who install Devbox with Nix to use pre-releases, and keep Devbox up-to-date on their system.

This changes our workflow in a few small ways:

1. Whenever go.mod changes, we'll need to run devbox run update-hash to update the vendorHash for the flake. You can also run this script when you run go mod tidy
2. Releasing a new version will also require us to update the version number in the flake.nix. This should be done with a commit ("Bump version to x.y") that also gets tagged with the release number.
3. For debugging purposes, the flake will add the shortened commit hash to the version string. This also helps identify if a user built the binary from a flake.
4. I've added a test to cli-tests that will build the flake. I've confirmed that it will fail if the vendorHash is out of date or incorrect
5. We'll periodically need to run nix flake update to update the flake.lock file.

How was it tested?

1. Ran nix build . in the Devbox repo, confirmed that the resulting build worked
2. Tested the Github Action by pushing an invalid vendorHash