Fix offline usage tracking and active pricelist sync

internal/services/quote.go

@@ -132,6 +132,11 @@ func (s *QuoteService) ValidateAndCalculate(req *QuoteRequest) (*QuoteValidation
 
 // RecordUsage records that components were used in a quote
 func (s *QuoteService) RecordUsage(items []models.ConfigItem) error {
+	if s.statsRepo == nil {
+		// Offline mode: usage stats are unavailable and should not block config saves.
+		return nil
+	}
+
 	for _, item := range items {
 		revenue := item.UnitPrice * float64(item.Quantity)
 		if err := s.statsRepo.IncrementUsage(item.LotName, item.Quantity, revenue); err != nil {