Fix nix build using FOD

[Chickensoupwithrice]

Finally a working nix build~

things still to do:

• allow building different flavors via nix
• configure the module to run it without a cookie, set up a bunch of other stuff. emulating pleroma seems like a good idea
• test that the nix shell dev environment works as well
• maybe set up a test container in the nix flake?

[Chickensoupwithrice]

This is a problem. I'll need to set some sort fallback here when git isn't available (it doesn't appear to be in the nix build process)

[Chickensoupwithrice]

are these the right commands to be running? If so see the changes necessary for the justfile

[Chickensoupwithrice]

Not really sure why I touched the mix.lock file either, might need to revert that