Model a Square for Restaurants menu using MENU_CATEGORY objects without breaking the REGULAR_CATEGORY structures that drive reporting and kitchen printer routing

Steps

1. Recognize that a Square 'menu' is not a separate object type from the catalog — it's built from CatalogItem/CatalogItemVariation objects organized under categories with category_type MENU_CATEGORY
2. Keep REGULAR_CATEGORY objects intact even if you add MENU_CATEGORY groupings for menu presentation, since REGULAR_CATEGORY still drives sales reporting and kitchen printer routing
3. When syncing menu changes from an external system, write item/variation data via the Catalog API's batch upsert, then separately manage MENU_CATEGORY membership for display grouping
4. Use CatalogModifierList and modifier overrides at the item level to represent item-specific modifier pricing rather than duplicating items per modifier combination
5. Query catalog objects with the appropriate object types filter to distinguish menu-presentation categories from operational (regular) categories when building sync logic