feat: comprehensive SEO system with keywords and schema markup

- Add 4-locale keyword configurations (SR, EN, DE, FR)
- Create schema generators (Product, Organization, Breadcrumb)
- Add React components for JSON-LD rendering
- Implement caching for keyword performance
- Abstract all SEO logic for maintainability

src/lib/seo/schema/productSchema.ts

@@ -0,0 +1,104 @@
+import { ProductSchema } from './types';
+import { Locale } from '../keywords/types';
+import { getBrandKeywords, getCategoryKeywords } from '../keywords';
+
+interface ProductData {
+  name: string;
+  slug: string;
+  description: string;
+  images: string[];
+  price: {
+    amount: number;
+    currency: string;
+  };
+  sku?: string;
+  availability?: 'InStock' | 'OutOfStock' | 'PreOrder';
+  category?: string;
+  rating?: {
+    value: number;
+    count: number;
+  };
+}
+
+/**
+ * Generate Product schema (JSON-LD)
+ * Pure function - takes product data, returns schema object
+ * 
+ * @param baseUrl - Site base URL
+ * @param locale - Locale code
+ * @param product - Product data
+ * @returns ProductSchema object
+ */
+export function generateProductSchema(
+  baseUrl: string,
+  locale: Locale,
+  product: ProductData
+): ProductSchema {
+  const brandKeywords = getBrandKeywords(locale);
+  const productUrl = `${baseUrl}/${locale === 'sr' ? '' : locale + '/'}products/${product.slug}`;
+  
+  // Build full image URLs
+  const imageUrls = product.images.map(img => 
+    img.startsWith('http') ? img : `${baseUrl}${img}`
+  );
+
+  const schema: ProductSchema = {
+    '@context': 'https://schema.org',
+    '@type': 'Product',
+    name: product.name,
+    image: imageUrls,
+    description: product.description.slice(0, 5000), // Schema.org limit
+    sku: product.sku,
+    brand: {
+      '@type': 'Brand',
+      name: brandKeywords.companyName,
+    },
+    offers: {
+      '@type': 'Offer',
+      url: productUrl,
+      price: product.price.amount.toString(),
+      priceCurrency: product.price.currency,
+      availability: `https://schema.org/${product.availability || 'InStock'}`,
+      itemCondition: 'https://schema.org/NewCondition',
+    },
+  };
+
+  // Add aggregate rating if available
+  if (product.rating && product.rating.count > 0) {
+    schema.aggregateRating = {
+      '@type': 'AggregateRating',
+      ratingValue: product.rating.value.toString(),
+      reviewCount: product.rating.count.toString(),
+    };
+  }
+
+  return schema;
+}
+
+/**
+ * Generate Product schema with category context
+ * Uses category-specific keywords for enhanced SEO
+ * 
+ * @param baseUrl - Site base URL
+ * @param locale - Locale code
+ * @param product - Product data
+ * @param categoryKey - Category key for keyword targeting
+ * @returns ProductSchema object
+ */
+export function generateCategorizedProductSchema(
+  baseUrl: string,
+  locale: Locale,
+  product: ProductData,
+  categoryKey: 'antiAging' | 'hydration' | 'glow' | 'sensitive' | 'natural' | 'organic'
+): ProductSchema {
+  const categoryKeywords = getCategoryKeywords(locale, categoryKey);
+  
+  // Enhance description with category keywords
+  const enhancedDescription = product.description + 
+    ' ' + categoryKeywords.slice(0, 3).join('. ');
+  
+  return generateProductSchema(baseUrl, locale, {
+    ...product,
+    description: enhancedDescription,
+  });
+}