nix: separate envs w.r.t. artifact guide

flake.nix

@@ -96,16 +96,22 @@
           download-m100-months = pkgs.mkShell {
             buildInputs = [
               packages.python-scripts
+              pkgs.coreutils # md5sum
+              pkgs.curl # curl
+              pkgs.gnutar # tar
             ];
           };
-          aggregate-power-m100-months = pkgs.mkShell {
+          merge-m100-power-predictions = pkgs.mkShell {
             buildInputs = [
               packages.python-scripts
+              pkgs.gnutar # tar
+              pkgs.gzip # gunzip
             ];
           };
-          use-python-scripts = pkgs.mkShell {
+          gen-simu-instances = pkgs.mkShell {
             buildInputs = [
               packages.python-scripts
+              pkgs.jq # jq
             ];
           };
           py-scripts = pkgs.mkShell {