fix(checkout): resolve currency constraint violations in price handling
- Add ensureCurrencyDefaults() helper to normalize price objects with EUR defaults
- Fix currency constraint violation in shopping cart item additions (bug #5405)
- Apply price normalization across availability, checkout, and shopping cart services
- Update 8 locations: availability.adapter, checkout.service, shopping-cart.service,
get-availability-params.adapter, availability-transformers, reward quantity control
- Refactor OrderType to @isa/common/data-access for cross-domain reusability
- Remove duplicate availability service from catalogue library
- Enhance PriceValue and VatValue schemas with proper currency defaults
- Add availability-transformers.spec.ts test coverage
- Fix QuantityControl fallback from 0 to 1 to prevent invalid state warnings
Resolves issue where POST requests to /checkout/v6/store/shoppingcart/{id}/item
were sending price objects without required currency/currencySymbol fields,
causing 400 Bad Request with 'Currency: Constraint violation: NotNull' error.
Related work items: #5405
- Add new reward-order-confirmation feature library with components and store
- Implement checkout completion orchestrator service for order finalization
- Migrate checkout/oms/crm models to Zod schemas for better type safety
- Add order creation facade and display order schemas
- Update shopping cart facade with order completion flow
- Add comprehensive tests for shopping cart facade
- Update routing to include order confirmation page
