refactor: eliminate hardcoded locale comparisons for antifragility

Created centralized helpers:
- src/lib/i18n/pageMetadata.ts: All page metadata (titles, descriptions, alt text)
- src/lib/i18n/productText.ts: Product-specific translated text (shortDescription, benefits)
- src/lib/i18n/metadata.ts: Helper functions for locale handling

Updated all pages to use centralized metadata:
- Homepage: Uses getPageMetadata for title, description, productionAlt
- Products page: Uses getPageMetadata
- Product detail: Uses getPageMetadata + getTranslatedShortDescription/getTranslatedBenefits
- About page: Uses getPageMetadata

ProductDetail component now uses:
- getTranslatedShortDescription() instead of locale comparison
- getTranslatedBenefits() instead of locale comparison

All user-facing text now goes through translation files or centralized helpers.
Adding a new language now requires only:
1. Add to SUPPORTED_LOCALES in locales.ts
2. Add LOCALE_CONFIG entry
3. Add entries to pageMetadata.ts and productText.ts
4. Add translation keys to message files

src/lib/i18n/productText.ts

@@ -0,0 +1,57 @@
+import type { Locale } from "./locales";
+
+const PRODUCT_TEXT: Record<Locale, {
+  defaultShortDescription: string;
+  defaultBenefits: string[];
+}> = {
+  sr: {
+    defaultShortDescription: "Premium prirodno ulje za vašu rutinu lepote.",
+    defaultBenefits: ["Prirodno", "Organsko", "Bez okrutnosti"],
+  },
+  en: {
+    defaultShortDescription: "Premium natural oil for your beauty routine.",
+    defaultBenefits: ["Natural", "Organic", "Cruelty-free"],
+  },
+  de: {
+    defaultShortDescription: "Premium natürliches Öl für Ihre Schönheitsroutine.",
+    defaultBenefits: ["Natürlich", "Bio", "Tierversuchsfrei"],
+  },
+  fr: {
+    defaultShortDescription: "Huile naturelle premium pour votre routine beauté.",
+    defaultBenefits: ["Naturel", "Bio", "Sans cruauté"],
+  },
+};
+
+export function getProductDefaults(locale: Locale) {
+  return PRODUCT_TEXT[locale] || PRODUCT_TEXT.en;
+}
+
+export function getTranslatedBenefits(
+  metadataBenefits: string[] | undefined,
+  locale: Locale
+): string[] {
+  const defaults = PRODUCT_TEXT[locale] || PRODUCT_TEXT.en;
+  
+  if (!metadataBenefits || metadataBenefits.length === 0) {
+    return defaults.defaultBenefits;
+  }
+  
+  return metadataBenefits.map((benefit, index) => {
+    const trimmed = benefit.trim();
+    if (!trimmed) {
+      return defaults.defaultBenefits[index] || trimmed;
+    }
+    return trimmed;
+  });
+}
+
+export function getTranslatedShortDescription(
+  description: string | undefined,
+  locale: Locale
+): string {
+  if (description && description.trim()) {
+    return description.split('.')[0] + '.';
+  }
+  const defaults = PRODUCT_TEXT[locale] || PRODUCT_TEXT.en;
+  return defaults.defaultShortDescription;
+}