extension.js imports ./dbus.js, but gnome-extensions pack never bundled it,
so the packed extension (the EGO zip) was missing the module and would fail
to load. Add dbus.js and the new util.js to the pack sources.
util.js holds the shared logError helper, replacing the per-file copies in
extension.js and panel.js and the raw console.error calls in clipboardItem.js.
