fix: jj sign commits

nix/users/luca/jj.nix

@@ -1,7 +1,14 @@
 {
   enable = true;
-  settings.user = {
+  settings = {
+    user = {
       email = "luca_lise@icloud.com";
       name = "lucalise";
     };
+    signing = {
+      behavior = "own";
+      backend = "ssh";
+      key = "~/.ssh/id_ed25519.pub";
+    };
+  };
 }

nix/users/luca/zsh.nix

@@ -33,6 +33,7 @@ in
       "rust"
       "kubectl"
       "helm"
+      "jj"
     ];
   };
   plugins = [