feat: Implement centralized module management system

- Add ModuleRegistry for managing built-in modules (newsletter, wishlist, affiliate, subscription, licensing)
- Add ModulesController REST API for module enable/disable
- Create Modules settings page with category grouping and toggle controls
- Integrate module checks across admin-spa and customer-spa
- Add useModules hook for both SPAs to check module status
- Hide newsletter from footer builder when module disabled
- Hide wishlist features when module disabled (product cards, account menu, wishlist page)
- Protect wishlist API endpoints with module checks
- Auto-update navigation tree when modules toggled
- Clean up obsolete documentation files
- Add comprehensive documentation:
  - MODULE_SYSTEM_IMPLEMENTATION.md
  - MODULE_INTEGRATION_SUMMARY.md
  - ADDON_MODULE_INTEGRATION.md (proposal)
  - ADDON_MODULE_DESIGN_DECISIONS.md (design doc)
  - FEATURE_ROADMAP.md
  - SHIPPING_INTEGRATION.md

Module system provides:
- Centralized enable/disable for all features
- Automatic navigation updates
- Frontend/backend integration
- Foundation for addon-module unification

customer-spa/src/pages/Account/components/AccountLayout.tsx

@@ -1,6 +1,7 @@
 import React, { ReactNode } from 'react';
 import { Link, useLocation } from 'react-router-dom';
 import { LayoutDashboard, ShoppingBag, Download, MapPin, Heart, User, LogOut } from 'lucide-react';
+import { useModules } from '@/hooks/useModules';
 
 interface AccountLayoutProps {
   children: ReactNode;
@@ -9,6 +10,7 @@ interface AccountLayoutProps {
 export function AccountLayout({ children }: AccountLayoutProps) {
   const location = useLocation();
   const user = (window as any).woonoowCustomer?.user;
+  const { isEnabled } = useModules();
   const wishlistEnabled = (window as any).woonoowCustomer?.settings?.wishlist_enabled !== false;
   
   const allMenuItems = [
@@ -20,9 +22,9 @@ export function AccountLayout({ children }: AccountLayoutProps) {
     { id: 'account-details', label: 'Account Details', path: '/my-account/account-details', icon: User },
   ];
   
-  // Filter out wishlist if disabled
+  // Filter out wishlist if module disabled or settings disabled
   const menuItems = allMenuItems.filter(item => 
-    item.id !== 'wishlist' || wishlistEnabled
+    item.id !== 'wishlist' || (isEnabled('wishlist') && wishlistEnabled)
   );
 
   const handleLogout = () => {