worf: Add yabai/skhd. Add sarek as builder

hosts/worf/configuration.nix

@@ -1,6 +1,9 @@
 { pkgs, ... }:
 {
   # Many settings should be handled by home manager. System-wide settings are however managed here.
+  imports = [
+    ./yabai.nix
+  ];
 
   nixpkgs.config.allowUnfree = true;
 
@@ -28,7 +31,18 @@
         mandatoryFeatures = [ ];
 
         sshUser = "felixalb";
-        sshKey = "/var/root/.ssh/nix-builder-voyager";
+        sshKey = "/var/root/.ssh/nix-builder";
+      }
+      {
+        hostName = "sarek.home.feal.no";
+        system = "x86_64-linux";
+
+        maxJobs = 6;
+        supportedFeatures = [ "big-parallel" "benchmark" "nixos-test" ];
+        mandatoryFeatures = [ ];
+
+        sshUser = "felixalb";
+        sshKey = "/var/root/.ssh/nix-builder";
       }
     ];