ci(nix): Add CI shell

shell.nix

@@ -41,10 +41,23 @@ pkgs.mkShellNoCC {
     ]
     ++ checks.enabledPackages;
 
+  # Environment variables
   ARGOCD_ENV_CLUSTER_NAME = "hel1";
   HELM_GIT_ACCESS_TOKEN = "glpat-xxx";
 
   shellHook = builtins.concatStringsSep "\n" [
     checks.shellHook
   ];
+
+  # Alternative shells
+  passthru = pkgs.lib.mapAttrs (name: value: pkgs.mkShellNoCC (value // { inherit name; })) {
+    ci-shell = {
+      packages = [
+        pkgs.npins
+      ];
+      shellHook = ''
+        export NPINS_DIRECTORY="nix"
+      '';
+    };
+  };
 }