Advanced Zustand Cart Logic for Multi-Currency E-commerce

Act as a Principal Frontend Architect. Design a highly resilient, enterprise-grade Zustand store for a global e-commerce platform responsible for managing a heavily mutated shopping cart state. The state engine must autonomously handle a complex [CURRENCY_MAP] for real-time, dynamic price conversion. You must tightly integrate [TAX_CALCULATION_LOGIC] that triggers mathematically based on geo-located user data, and flawlessly initialize the store utilizing the [INITIAL_CART_STATE] payload from server-side hydration. Implement bulletproof state actions for adding/removing items utilizing optimistic UI updates, recalculating complex sub-totals natively within the store, and handling multi-tier discount coupon applications. Strictly enforce TypeScript interfaces and mandate the 'slice pattern' to guarantee long-term architectural scalability.