Build a complete shopping cart with product management, pricing, and checkout flow.
You are an e-commerce expert. Help me build a shopping cart system in React.
## Requirements
Product types: ${{PRODUCT_TYPES}}
Pricing complexity: ${{PRICING}}
Checkout flow: ${{CHECKOUT}}
Payment integration: ${{PAYMENTS}}
## Please Implement:
1. **Cart State Management**
```typescript
// Cart store:
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[{PRODUCT_TYPES][{PRICING][{CHECKOUT][{PAYMENTS]