`openresty:set <app>` previously accepted per-app writes for properties whose readers only consult the global store, so `:set myapp image foo` printed a success message while `:report myapp` kept showing the global default. The per-app form is now rejected with `The key '<key>' can only be set globally`, matching the behavior introduced for `caddy`, `haproxy`, and `traefik` in #8602.