move nixops4 to overlay

panel/nix/configuration.nix

@@ -2,7 +2,6 @@
   config,
   pkgs,
   lib,
-  inputs,
   ...
 }:
 let
@@ -148,19 +147,7 @@ in
         NixOps4 from the package's npins-based code, we will have to do with
         this workaround.
       '';
-      default =
+      default = pkgs.nixops4;
-        let
-          sources = import ../../npins;
-          inherit (import sources.flake-inputs) import-flake load-flake;
-          inherit
-            (import-flake {
-              src = ../../.;
-            })
-            inputs
-            ;
-          inherit (inputs) nixops4;
-        in
-        (load-flake nixops4).packages.${pkgs.system}.default;
     };
 
     deployment = {

panel/nix/overlay.nix

@@ -8,4 +8,17 @@ let
 in
 {
   python3 = prev.lib.attrsets.recursiveUpdate prev.python3 { pkgs = extraPython3Packages; };
+  nixops4 =
+    let
+      sources = import ../../npins;
+      inherit (import sources.flake-inputs) import-flake load-flake;
+      inherit
+        (import-flake {
+          src = ../../.;
+        })
+        inputs
+        ;
+      inherit (inputs) nixops4;
+    in
+    (load-flake nixops4).packages.${prev.system}.default;
 }