feat: Initialize customer-spa project structure

Sprint 1 - Foundation Setup:

Created customer-spa/ folder structure:
```
customer-spa/
├── src/
│   ├── pages/          # Customer pages (Shop, Cart, Checkout, Account)
│   ├── components/     # Reusable components
│   ├── lib/
│   │   ├── api/        # API client
│   │   ├── cart/       # Cart state management
│   │   ├── checkout/   # Checkout logic
│   │   └── tracking/   # Analytics & pixel tracking
│   ├── hooks/          # Custom React hooks
│   ├── contexts/       # React contexts
│   └── types/          # TypeScript types
├── public/             # Static assets
├── package.json        # Dependencies
├── vite.config.ts      # Vite configuration (port 5174)
├── tsconfig.json       # TypeScript configuration
├── tailwind.config.js  # TailwindCSS configuration
├── postcss.config.js   # PostCSS configuration
└── .eslintrc.cjs       # ESLint configuration
```

Configuration:
✅ Vite dev server on port 5174 (admin-spa uses 5173)
✅ HTTPS with shared SSL cert
✅ TypeScript + React 18
✅ TailwindCSS + shadcn/ui
✅ React Query for data fetching
✅ Zustand for state management
✅ React Hook Form + Zod for forms
✅ React Router for routing

Dependencies Added:
- Core: React 18, React DOM, React Router
- UI: Radix UI components, Lucide icons
- State: Zustand, TanStack Query
- Forms: React Hook Form, Zod, @hookform/resolvers
- Styling: TailwindCSS, class-variance-authority
- Utils: clsx, tailwind-merge, sonner (toast)

Next Steps:
- Create main.tsx entry point
- Create App.tsx with routing
- Create base layout components
- Setup API client
- Implement cart state management

Ready for Sprint 1 implementation!

customer-spa/.eslintrc.cjs

@@ -0,0 +1,20 @@
+module.exports = {
+  root: true,
+  env: { browser: true, es2020: true },
+  extends: [
+    'eslint:recommended',
+    'plugin:@typescript-eslint/recommended',
+    'plugin:react-hooks/recommended',
+  ],
+  ignorePatterns: ['dist', '.eslintrc.cjs', 'eslint.config.js'],
+  parser: '@typescript-eslint/parser',
+  plugins: ['react-refresh'],
+  rules: {
+    'react-refresh/only-export-components': [
+      'warn',
+      { allowConstantExport: true },
+    ],
+    '@typescript-eslint/no-explicit-any': 'off',
+    '@typescript-eslint/no-unused-vars': ['warn', { argsIgnorePattern: '^_', varsIgnorePattern: '^_' }],
+  },
+}