add atuin key as clan var

modules/dev.nix

@@ -0,0 +1,6 @@
+{
+  clan.core.vars.generators.atuin = {
+    prompts.key.persist = true;
+    files.key.owner = "rpqt";
+  };
+}

modules/flake-module.nix

@@ -9,6 +9,7 @@
       ./desktop.nix
     ];
 
+    dev.imports = [ ./dev.nix ];
     nix-defaults.imports = [ ./nix-defaults.nix ];
     tailscale.imports = [ ./tailscale.nix ];
     user-rpqt.imports = [ ./user-rpqt.nix ];