feat: add lib to flake

.envrc

@@ -1 +0,0 @@
-use flake

flake.nix

@@ -20,14 +20,14 @@
         # module parameters provide easy access to attributes of the same
         # system.
 
-        # Equivalent to  inputs'.nixpkgs.legacyPackages.hello;
-        packages.default = pkgs.hello;
+        packages.lib = import ./lib.nix { inherit pkgs; };
       };
       flake = {
         # The usual flake attributes can be defined here, including system-
         # agnostic ones like nixosModule and system-enumerating ones, although
         # those are more easily expressed in perSystem.
 
+        lib = import ./lib.nix;
       };
     };
 }