nixos/tandoor-recipes: Fix working directory

Run `tandoor-recipes` from within its `MEDIA_ROOT` directory to support
the `SCRIPT_NAME` setting.

Closes #262857.

nixos/modules/services/misc/tandoor-recipes.nix

@@ -22,7 +22,7 @@ let
     ${lib.toShellVars env}
     eval "$(${config.systemd.package}/bin/systemctl show -pUID,GID,MainPID tandoor-recipes.service)"
     exec ${pkgs.util-linux}/bin/nsenter \
-      -t $MainPID -m -S $UID -G $GID \
+      -t $MainPID -m -S $UID -G $GID --wdns=${env.MEDIA_ROOT} \
       ${pkg}/bin/tandoor-recipes "$@"
   '';
 in