Simplify build-related config

colmena/local.nix

@@ -0,0 +1,14 @@
+{ name, nodes, config, lib, pkgs, ... }:
+
+{
+  deployment = {
+    allowLocalDeployment = true;
+    targetHost = null;
+    tags = [ "local" ];
+  };
+
+  environment.systemPackages = with pkgs; [
+    colmena
+    npins
+  ];
+}

colmena/remote.nix

@@ -0,0 +1,12 @@
+{ name, nodes, config, lib, pkgs, ... }:
+
+{
+  deployment = {
+    targetHost = "${name}.birdsong.network";
+    tags = [ "remote" ];
+  };
+
+  imports = [
+    ../services/openssh.nix
+  ];
+}