Product and menu discovery

1. The model calls getAvailableStores.
2. For retail it calls discoverProducts. For food it calls discoverRestaurantMenus.
3. A discovery card shows matches grouped by store.
4. Opening one calls getProduct and shows variants.

getAvailableCountries and getAvailableRegions give the shipping destinations. The Openfront adapter uses the store's regions query to resolve a country to a region.

If nothing matches the app answers No <vertical> results matched the requested items, location, and country. If no store of that vertical is admitted: No admitted <vertical> sources match this request.

Retail discovery uses SearchProducts and GetProduct. Restaurant discovery uses MarketplaceRestaurantMenu and MarketplaceMenuItem. See GraphQL operations.