QC-67: Customer app shell + shops/cart/orders navigation

[DarshanCode2005]

Summary

Customer app shell + shops/cart/orders navigation

Milestone: M2 Customer
Labels: frontend, customer, design

Learn

• Zustand cart store totals across shops
• Layout-level navigation vs page-level FloatingCartBar
• Mobile bottom nav patterns

Build

• Create components/layout/CustomerNav.tsx — Shops | Cart (badge) | Orders
• Cart badge = total line qty across all shops (useCartStore)
• Integrate into app/(customer)/layout.tsx on all customer pages
• Coordinate FloatingCartBar on shop detail so it sits above bottom nav (no overlap)
• Header: customer name + Sign out
• Ensure nav visible on shops list, shop detail, cart, checkout, orders

Files

• components/layout/CustomerNav.tsx
• app/(customer)/layout.tsx
• components/customer/FloatingCartBar.tsx
• lib/routes.ts

Acceptance criteria

• Customer moves between shops, cart, and orders without typing URLs
• Cart badge updates after add-to-cart on shop detail
• Nav persists across full browse → cart → checkout → orders flow
• Sign out works from customer area
• 44px min touch targets on mobile tabs

Depends on

• QC-19: Shop listing page UI + skeletons #121 (QC-19)
• QC-24: Cart page + order summary #25 (QC-24)
• QC-29: Customer orders list page #30 (QC-29)