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/metadata.ts

@@ -1,17 +1,37 @@
-import { DEFAULT_LOCALE, LOCALE_CONFIG, type Locale } from "./locales";
-
-export function getMetadataText(locale: Locale, texts: Partial<Record<Locale, string>>): string {
-  return texts[locale] || texts[DEFAULT_LOCALE] || "";
-}
+import { DEFAULT_LOCALE, LOCALE_CONFIG, SUPPORTED_LOCALES, type Locale } from "./locales";
 
 export function getSaleorLocale(locale: Locale): string {
   return LOCALE_CONFIG[locale].saleorLocale;
 }
 
-export function getLocaleDisplayName(locale: Locale): string {
+export function getLocaleLabel(locale: Locale): string {
   return LOCALE_CONFIG[locale].label;
 }
 
 export function isDefaultLocale(locale: string): boolean {
   return locale === DEFAULT_LOCALE;
 }
+
+export function getLocaleFromParams(params: { locale: string }): Locale {
+  const { locale } = params;
+  if (SUPPORTED_LOCALES.includes(locale as Locale)) {
+    return locale as Locale;
+  }
+  return DEFAULT_LOCALE;
+}
+
+export function getProductLocale(locale: Locale): string {
+  return getSaleorLocale(locale);
+}
+
+export function buildHreflangAlternates(baseUrl: string): Record<string, string> {
+  const alternates: Record<string, string> = {};
+  for (const loc of SUPPORTED_LOCALES) {
+    if (loc === DEFAULT_LOCALE) {
+      alternates[loc] = baseUrl;
+    } else {
+      alternates[loc] = `${baseUrl}/${loc}`;
+    }
+  }
+  return alternates;
+}