Add automatic cleanup

hosts/modules/base.nix

@@ -64,6 +64,15 @@
   # Enable the Flakes feature and the accompanying new nix command-line tool
   nix.settings.experimental-features = [ "nix-command" "flakes" ];
 
+  # some nix tidy up stuff
+  nix.settings.auto-optimise-store = true;
+
+  nix.gc = {
+    automatic = true;
+    dates = "weekly";
+    options = "--delete-older-than 30d";
+  };
+
   # Enable zeroconf
   services.avahi = {
     enable = true;