Enable the build VM as a substituter.

This should enable me to have local build jobs without rebuilding stuff that already exists on the build VM server.

nix/configuration/hosts/quark/distributed_build.nix

@@ -8,6 +8,7 @@
       additional_config = {
         speedFactor = 2;
       };
+      substituter_url = "ssh-ng://nixworker@ns1.fizz.buzz:65122?compress=true&ssh-key=/persist/manual/ssh/root/keys/id_ed25519&remote-store=local?root=/.disk/root";
     };
   };
 }