feat: Add-to-cart from URL parameters

Implements direct-to-cart functionality for landing page CTAs.

Features:
- Parse URL parameters: ?add-to-cart=123
- Support simple products: ?add-to-cart=123
- Support variable products: ?add-to-cart=123&variation_id=456
- Support quantity: ?add-to-cart=123&quantity=2
- Auto-navigate to cart after adding
- Clean URL after adding (remove parameters)
- Toast notification on success/error

Usage examples:
1. Simple product:
   https://site.com/store?add-to-cart=332

2. Variable product:
   https://site.com/store?add-to-cart=332&variation_id=456

3. With quantity:
   https://site.com/store?add-to-cart=332&quantity=3

Flow:
- User clicks CTA on landing page
- Redirects to SPA with add-to-cart parameter
- SPA loads, hook detects parameter
- Adds product to cart via API
- Navigates to cart page
- Shows success toast

Works with both SPA modes:
- Full SPA: loads shop, adds to cart, navigates to cart
- Checkout Only: loads cart, adds to cart, stays on cart

customer-spa/src/hooks/useAddToCartFromUrl.ts

@@ -0,0 +1,95 @@
+import { useEffect } from 'react';
+import { useNavigate, useLocation } from 'react-router-dom';
+import { toast } from 'sonner';
+
+/**
+ * Hook to handle add-to-cart from URL parameters
+ * Supports both simple and variable products
+ * 
+ * URL formats:
+ * - Simple product: ?add-to-cart=123
+ * - Variable product: ?add-to-cart=123&variation_id=456
+ * - With quantity: ?add-to-cart=123&quantity=2
+ */
+export function useAddToCartFromUrl() {
+  const navigate = useNavigate();
+  const location = useLocation();
+
+  useEffect(() => {
+    const params = new URLSearchParams(window.location.search);
+    const productId = params.get('add-to-cart');
+    
+    if (!productId) return;
+
+    const variationId = params.get('variation_id');
+    const quantity = parseInt(params.get('quantity') || '1', 10);
+
+    console.log('[WooNooW] Add to cart from URL:', {
+      productId,
+      variationId,
+      quantity,
+      fullUrl: window.location.href,
+    });
+
+    // Add product to cart
+    addToCart(productId, variationId, quantity)
+      .then(() => {
+        // Remove URL parameters after adding to cart
+        const cleanUrl = window.location.pathname + window.location.hash;
+        window.history.replaceState({}, '', cleanUrl);
+        
+        // Navigate to cart if not already there
+        if (!location.pathname.includes('/cart')) {
+          navigate('/cart');
+        }
+      })
+      .catch((error) => {
+        console.error('[WooNooW] Failed to add product to cart:', error);
+        toast.error('Failed to add product to cart');
+      });
+  }, []); // Run once on mount
+}
+
+async function addToCart(
+  productId: string,
+  variationId: string | null,
+  quantity: number
+): Promise<void> {
+  const apiRoot = (window as any).woonoowCustomer?.apiRoot || '/wp-json/woonoow/v1';
+  const nonce = (window as any).woonoowCustomer?.nonce || '';
+
+  const body: any = {
+    product_id: parseInt(productId, 10),
+    quantity,
+  };
+
+  if (variationId) {
+    body.variation_id = parseInt(variationId, 10);
+  }
+
+  console.log('[WooNooW] Adding to cart:', body);
+
+  const response = await fetch(`${apiRoot}/cart/add`, {
+    method: 'POST',
+    headers: {
+      'Content-Type': 'application/json',
+      'X-WP-Nonce': nonce,
+    },
+    credentials: 'include',
+    body: JSON.stringify(body),
+  });
+
+  if (!response.ok) {
+    const errorData = await response.json().catch(() => ({}));
+    throw new Error(errorData.message || 'Failed to add to cart');
+  }
+
+  const data = await response.json();
+  
+  if (!data.success) {
+    throw new Error(data.message || 'Failed to add to cart');
+  }
+
+  console.log('[WooNooW] Product added to cart:', data);
+  toast.success('Product added to cart');
+}