Unified aggregator for the menu family's configuration. Filters features
by _target and forwards to the matching provide*Config function.
Today there is exactly one config surface (CNGX_MENU_CONFIG), so all
features dispatch to provideMenuConfig. The discriminator
scaffolding is in place so adding a future surface does not break the
public API of existing with* features.
Mirrors provideCngxSelect from the select-family A+ closure.