feat(seo): add short description to product LLM text

Include kurzBeschreibung in the generated LLM-friendly product details
for better SEO context, if available.

prerender/seo/llms.cjs

@@ -183,7 +183,13 @@ This file contains products ${startIndex + 1}-${endIndex} of ${totalProducts} in
         categoryLlmsTxt += `## ${globalIndex}. ${product.name}
 
 - **Product URL**: ${baseUrl}/Artikel/${product.seoName}
-- **Article Number**: ${product.articleNumber || 'N/A'}
+`;
+
+        if (product.kurzBeschreibung) {
+          categoryLlmsTxt += `- **Desc:** ${product.kurzBeschreibung}\n`;
+        }
+
+        categoryLlmsTxt += `- **Article Number**: ${product.articleNumber || 'N/A'}
 - **Price**: €${product.price || '0.00'}
 - **Brand**: ${product.manufacturer || config.brandName}
 - **Availability**: ${product.available ? 'In Stock' : 'Out of Stock'}`;