fix: i18n gaps in popular searches and compare table

- SearchFacade.popularSearches hardcoded English titles regardless of
  active locale. Converted to a getter using translate.t() for the
  displayed title/text; the underlying search query stays the stable
  English canonical term the backend index matches against.
- Compare table and compare page rendered product.name raw instead of
  through getTranslatedField(), same pattern used everywhere else
  product titles are shown (catalog, product detail).
- SearchTrendingService.loadTrending() is a genuine backend gap (no
  trending-search endpoint exists) - already degrades gracefully,
  documented as a gap in BACKEND-API-REFERENCE.md \u00a712.6 rather than
  faked client-side.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/i18n/ru.ts

@@ -144,6 +144,10 @@ export const ru: Translations = {
     noResultsHint: 'Попробуйте изменить запрос или используйте другие ключевые слова',
     emptyResultsAria: 'Пустые результаты поиска',
     popularCategories: 'Популярные категории',
+    popularSmartphones: 'Смартфоны',
+    popularSneakers: 'Кроссовки',
+    popularHeadphones: 'Наушники',
+    popularLaptops: 'Ноутбуки',
     recommendedProducts: 'Рекомендуемые товары',
     aiSuggestionHint: 'AI-подсказка (в будущем)',
     suggestionType: {