set default terminal to ghostty

nixos/modules/gui/niri.nix

@@ -19,7 +19,14 @@ in
       kdePackages.qt6ct
       libsForQt5.qt5ct
     ];
-    xdg.mime = {
+    xdg = {
+      terminal-exec = {
+        enable = true;
+        settings = {
+          default = [ "com.mitchellh.ghostty.desktop" ];
+        };
+      };
+      mime = {
         enable = true;
         defaultApplications = {
           "inode/directory" = [
@@ -52,6 +59,7 @@ in
           ];
         };
       };
+    };
     hardware.bluetooth = {
       enable = true;
     };