refactor: rename utils to lib'

lib/hosts.nix

@@ -0,0 +1,23 @@
+{ lib }:
+
+let
+  fs = import ./fs.nix { inherit lib; };
+
+  hostsPath = ../hosts;
+  hostMeta =
+    host:
+    let
+      metaPath = hostsPath + "/${host}/meta.nix";
+    in
+    if builtins.pathExists metaPath then
+      import metaPath
+    else
+      throw "meta.nix required in ${toString metaPath}";
+  hostNames = fs.dirNames hostsPath;
+in
+{
+  inherit hostsPath hostMeta hostNames;
+
+  adminHosts = builtins.filter (host: (hostMeta host).host.admin or false) hostNames;
+  nixosHosts = hostNames;
+}