feat: Implement Phase 6 Shopping and Checkout

- Introduced authenticated shopping state and atomic checkout process without creating orders or payments.
- Reused existing components from previous phases including identities, addresses, catalogues, pricing, and inventory.
- Developed cart architecture to support one active cart per user with unique items per variant.
- Implemented dynamic cart pricing with various precedence rules for promotions and coupons.
- Created a wishlist feature that exposes only visible active products without reserving inventory.
- Integrated inventory validation to ensure availability of items before adding to cart.
- Developed a checkout architecture that locks the cart, revalidates pricing and shipping, and reserves inventory.
- Added shipping zones, methods, and rates with configurable options for international shipping and duty/tax boundaries.
- Implemented checkout snapshots to capture immutable checkout details.
- Introduced idempotency for checkout requests to prevent duplicate processing.
- Added functionality for coupon integration and business checkout validation.
- Established permissions for managing shipping zones, methods, and rates.
- Created comprehensive unit tests covering various aspects of the shopping and checkout processes.
- Added cron job for handling checkout expiry reconciliation.
- Created migration script to set up new database tables and constraints for carts, checkout sessions, and shipping.

cron/index.js

@@ -11,11 +11,12 @@
 
 const startCleanInactiveNotificationsCron = require("./notificationCleaning.cron");
 const startInventoryReservationExpiryCron = require("./inventoryReservationExpiry.cron");
+const startCheckoutExpiryCron = require("./checkoutExpiry.cron");
 
 function startAllCrons() {
   console.log("Starting Cron Jobs...");
 
-  const tasks = [startCleanInactiveNotificationsCron(), startInventoryReservationExpiryCron()];
+  const tasks = [startCleanInactiveNotificationsCron(), startInventoryReservationExpiryCron(), startCheckoutExpiryCron()];
 
   return async () => {
     for (const task of tasks) {