feat: initial v3 rewrite

lib/impl/jobDeps.nix

@@ -0,0 +1,35 @@
+{
+  lib,
+  helpers,
+}: let
+  inherit (lib) concatLines mapAttrsToList makeBinPath;
+  inherit (helpers) filterJobVariables stdenvMinimal;
+in
+  {
+    key,
+    job,
+    nixConfig,
+  }: let
+    variablesWithStorePaths = filterJobVariables true job;
+    variableExports = concatLines (
+      mapAttrsToList (name: value: "export ${name}=\"${value}\"") variablesWithStorePaths
+    );
+    script = ''
+      export PATH="${makeBinPath (nixConfig.deps or [])}:$PATH";
+      # variables containing nix derivations:
+      ${variableExports}
+    '';
+  in
+    stdenvMinimal.mkDerivation {
+      name = "gitlab-ci-job-deps-${key}";
+      dontUnpack = true;
+      installPhase =
+        # sh
+        ''
+          echo '${script}' > $out
+          chmod +x $out
+        '';
+      passthru = {
+        inherit script;
+      };
+    }