Implement AI recommendations for multiple companies and enhance company context handling

- Added functionality to retrieve merged AI recommendations for multiple companies, improving the relevance of tender suggestions based on company-specific data.
- Introduced normalization functions to clean and deduplicate company IDs, ensuring accurate processing of recommendations.
- Enhanced the company context resolution in customer middleware to support multiple assigned companies, improving the handling of company-specific requests.
- Updated the tender recommendation logic to utilize the new merged recommendations and handle exclusions for rejected tenders accordingly.
- Added unit tests to verify the new recommendation merging logic and company ID normalization, ensuring robust functionality.

This update significantly enhances the tender recommendation process by allowing for more comprehensive and relevant suggestions based on multiple company contexts, improving user experience and satisfaction.

internal/company/recommendation.go

@@ -24,6 +24,44 @@ const (
 	recommendationFetchInitialDelay = 10 * time.Second
 )
 
+func normalizeRecommendationCompanyIDs(companyIDs []string) []string {
+	normalized := make([]string, 0, len(companyIDs))
+	seen := make(map[string]struct{}, len(companyIDs))
+	for _, companyID := range companyIDs {
+		clean := strings.TrimSpace(companyID)
+		if clean == "" {
+			continue
+		}
+		if _, ok := seen[clean]; ok {
+			continue
+		}
+		seen[clean] = struct{}{}
+		normalized = append(normalized, clean)
+	}
+	return normalized
+}
+
+func mergeRecommendedTenders(recommendationLists ...[]RecommendedTenderResponse) []RecommendedTenderResponse {
+	merged := make([]RecommendedTenderResponse, 0)
+	seen := make(map[string]struct{})
+	for _, recommendations := range recommendationLists {
+		for _, recommendation := range recommendations {
+			tenderID := strings.TrimSpace(recommendation.TenderID)
+			if tenderID == "" {
+				continue
+			}
+			if _, ok := seen[tenderID]; ok {
+				continue
+			}
+			seen[tenderID] = struct{}{}
+			recommendation.TenderID = tenderID
+			recommendation.Analysis = strings.TrimSpace(recommendation.Analysis)
+			merged = append(merged, recommendation)
+		}
+	}
+	return merged
+}
+
 func aiRecommendationCacheKey(companyID string) string {
 	return aiRecommendationCacheKeyPrefix + companyID
 }
@@ -182,6 +220,29 @@ func (s *companyService) GetAIRecommendations(ctx context.Context, companyID str
 	return []RecommendedTenderResponse{}, nil
 }
 
+// GetMergedAIRecommendations unions cached AI recommendations across multiple companies.
+func (s *companyService) GetMergedAIRecommendations(ctx context.Context, companyIDs []string) ([]RecommendedTenderResponse, error) {
+	if s.aiRecommendationClient == nil {
+		return nil, ErrAIRecommendationNotConfigured
+	}
+
+	normalized := normalizeRecommendationCompanyIDs(companyIDs)
+	if len(normalized) == 0 {
+		return []RecommendedTenderResponse{}, nil
+	}
+
+	recommendationLists := make([][]RecommendedTenderResponse, 0, len(normalized))
+	for _, companyID := range normalized {
+		recommendations, err := s.GetAIRecommendations(ctx, companyID)
+		if err != nil {
+			return nil, err
+		}
+		recommendationLists = append(recommendationLists, recommendations)
+	}
+
+	return mergeRecommendedTenders(recommendationLists...), nil
+}
+
 func (s *companyService) scheduleRecommendationRefreshAfterOnboarding(companyID string) {
 	if s.aiRecommendationClient == nil {
 		return