Refactor recommendation page cache handling and configuration

- Removed the `RecommendationPageCacheLanguages` configuration from `AISummarizerConfig` to streamline cache management.
- Updated the `companyService` and `tenderService` to utilize the new `InvalidateRecommendedTendersPageCache` method for cache invalidation, enhancing clarity and efficiency.
- Refactored the `invalidateRecommendedTendersPageCache` method to eliminate unnecessary context parameters, simplifying the function signature.
- Improved the handling of page cache refresh logic by consolidating language handling within the `tenderService`, ensuring consistent behavior across services.
- Cleaned up related tests and removed deprecated functions to maintain code quality and readability.

This update enhances the maintainability of the recommendation caching system by simplifying configuration and improving cache invalidation logic.

internal/tender/service.go

@@ -92,7 +92,6 @@ type tenderService struct {
 	aiSummarizerStorage  AISummarizerStorage
 	redisClient          redis.Client
 	pageCacheTTL         time.Duration
-	pageCacheLanguages   []string
 	defaultLanguage      string
 }
 
@@ -117,7 +116,6 @@ func NewService(
 	aiStorage AISummarizerStorage,
 	redisClient redis.Client,
 	recommendationPageCacheTTL time.Duration,
-	recommendationPageCacheLanguages []string,
 	defaultLanguage string,
 ) Service {
 	if strings.TrimSpace(defaultLanguage) == "" {
@@ -134,7 +132,6 @@ func NewService(
 		aiSummarizerStorage:  aiStorage,
 		redisClient:          redisClient,
 		pageCacheTTL:         recommendationPageCacheTTL,
-		pageCacheLanguages:   normalizePageCacheLanguages(defaultLanguage, recommendationPageCacheLanguages),
 		defaultLanguage:      strings.ToLower(defaultLanguage),
 	}
 }
@@ -999,7 +996,7 @@ func (s *tenderService) Recommend(ctx context.Context, form *SearchForm, paginat
 	}
 
 	if len(companyIDs) == 0 && companyID != "" {
-		s.ScheduleRefreshRecommendedTendersPageCache(companyID)
+		s.schedulePageCacheRefreshForLanguage(companyID, lang)
 	}
 
 	excluded, excludedByCompany, err := s.loadRecommendationExclusions(ctx, form, companyID, companyIDs)
@@ -1030,7 +1027,7 @@ func (s *tenderService) Recommend(ctx context.Context, form *SearchForm, paginat
 		return nil, err
 	}
 
-	paged := s.buildRecommendedTenderListResponses(pageResult.items, lang)
+	paged := s.buildRecommendedTenderResponsesParallel(ctx, pageResult.items, lang)
 
 	return &SearchResponse{
 		Tenders:  paged,