fetchBanners abstract method
Load banners for a placement (e.g. home_hero, cart_footer).
placement - Optional identifier describing where the banners will render.
locale - Optional locale/language hint for localized campaigns.
filters - Extra backend-specific filters (e.g., tags, customer group).
Implementation
Future<List<PromoBanner>> fetchBanners({
String? placement,
String? locale,
Map<String, dynamic>? filters,
});