feat(flake): clean up

Move helpers to `./helpers.nix`

lib/helpers.nix

@@ -1,36 +0,0 @@
-{ lib, ... }:
-
-let
-  inherit (lib) mapAttrs;
-  inherit (lib.attrsets) filterAttrs;
-in
-rec {
-  recurseDir = dir:
-    mapAttrs
-      (file: type:
-        if type == "directory"
-        then recurseDir "${dir}/${file}"
-        else type
-      )
-      (builtins.readDir dir);
-
-  # VVV - Implying `attrs` is the output of `recurseDir` - VVV
-
-  hasFiles = files: attrs:
-    builtins.all
-      (b: b)
-      (builtins.map
-        (file:
-          builtins.hasAttr file attrs &&
-          builtins.getAttr file attrs == "regular")
-        files);
-
-  hasDirectories = directories: attrs:
-    builtins.all
-      (b: b)
-      (builtins.map
-        (directory:
-          builtins.hasAttr directory attrs &&
-          builtins.getAttr directory attrs == "set")
-        directories);
-}