Build an Order Processing Service

Problem/Feature Description

Build an order processing backend service using Express and TypeScript. The service will be deployed in a Kubernetes cluster and sits behind a service mesh. It connects to a PostgreSQL database and a Redis cache.

Endpoints:

• POST /api/orders -- create an order (fields: customerId, items array with productId and quantity)
• GET /api/orders/:id -- get order by ID
• GET /api/orders?customerId=X -- list orders for a customer
• PATCH /api/orders/:id/status -- update order status (pending, confirmed, shipped, delivered)

Assume database and Redis connection modules already exist as db.ts (exports a pool with .query()) and cache.ts (exports a redis client with .get()/.set()/.ping()). You do NOT need to implement these -- just import and use them.

Output Specification

Produce:

• src/app.ts -- Express application with middleware and route setup
• src/routes/orders.ts -- Order route handlers
• src/types.ts -- TypeScript interfaces for Order, OrderItem
• package.json -- With dependencies
• k8s/deployment.yaml -- Kubernetes Deployment manifest for this service