feat: Newsletter system improvements and validation framework

- Fix: Marketing events now display in Staff notifications tab
- Reorganize: Move Coupons to Marketing/Coupons for better organization
- Add: Comprehensive email/phone validation with extensible filter hooks
  - Email validation with regex pattern (xxxx@xxxx.xx)
  - Phone validation with WhatsApp verification support
  - Filter hooks for external API integration (QuickEmailVerification, etc.)
- Fix: Newsletter template routes now use centralized notification email builder
- Add: Validation.php class for reusable validation logic
- Add: VALIDATION_HOOKS.md documentation with integration examples
- Add: NEWSLETTER_CAMPAIGN_PLAN.md architecture for future campaign system
- Fix: API delete method call in Newsletter.tsx (delete -> del)
- Remove: Duplicate EmailTemplates.tsx (using notification system instead)
- Update: Newsletter controller to use centralized Validation class

Breaking changes:
- Coupons routes moved from /routes/Coupons to /routes/Marketing/Coupons
- Legacy /coupons routes maintained for backward compatibility

customer-spa/src/layouts/BaseLayout.tsx

@@ -1,6 +1,6 @@
 import React, { ReactNode, useState } from 'react';
 import { Link } from 'react-router-dom';
-import { ShoppingCart, User, Search, Menu, X } from 'lucide-react';
+import { Search, ShoppingCart, User, Menu, X, Heart } from 'lucide-react';
 import { useLayout } from '../contexts/ThemeContext';
 import { useCartStore } from '../lib/cart/store';
 import { useHeaderSettings, useFooterSettings } from '../hooks/useAppearanceSettings';
@@ -130,6 +130,14 @@ function ClassicLayout({ children }: BaseLayoutProps) {
                 </a>
               ))}
               
+              {/* Wishlist */}
+              {headerSettings.elements.wishlist && (window as any).woonoowCustomer?.settings?.wishlist_enabled !== false && user?.isLoggedIn && (
+                <Link to="/my-account/wishlist" className="flex items-center gap-2 text-sm font-medium text-gray-700 hover:text-gray-900 transition-colors no-underline">
+                  <Heart className="h-5 w-5" />
+                  <span className="hidden lg:block">Wishlist</span>
+                </Link>
+              )}
+              
                 {/* Cart */}
                 {headerSettings.elements.cart && (
                   <Link to="/cart" className="flex items-center gap-2 text-sm font-medium text-gray-700 hover:text-gray-900 transition-colors no-underline">