Enhance tender estimated value resolution and add unit tests

- Updated the `ResolvedEstimatedValueAndCurrency` method to aggregate procurement lot values when the tender-level estimated value is not set, improving accuracy in value retrieval.
- Introduced the `AggregateProcurementLotEstimatedValue` function to sum estimated values from procurement lots and return the first found currency.
- Modified the `ToResponseWithLanguage` method to utilize the new estimated value resolution logic.
- Added unit tests for the new functionality, ensuring correct behavior for various scenarios in the `entity_test.go` and `budget_test.go` files.

This update improves the handling of estimated values in tenders, enhancing the overall reliability of the tender management system.

cmd/worker/workers/notice.go

@@ -476,6 +476,16 @@ func (w *NoticeWorker) ToTender(n *notice.Notice) (*tender.Tender, error) {
 		awardedEntities = mergeAwardedEntitiesByLotID(t.AwardedEntities, awardedEntities)
 		title, description = mergeTitleAndDescriptionForMultiLot(t.Title, t.Description, title, description)
 
+		if estimatedVal == 0 && t.EstimatedValue > 0 {
+			estimatedVal = t.EstimatedValue
+		}
+		if awardedVal == 0 && t.AwardedValue > 0 {
+			awardedVal = t.AwardedValue
+		}
+		if currency == "" && t.Currency != "" {
+			currency = t.Currency
+		}
+
 		if strings.TrimSpace(previousNoticePublicationID) != "" && previousNoticePublicationID != n.NoticePublicationID {
 			if n.EstimatedValue > 0 {
 				estimatedVal = t.EstimatedValue + n.EstimatedValue
@@ -495,6 +505,15 @@ func (w *NoticeWorker) ToTender(n *notice.Notice) (*tender.Tender, error) {
 		}
 	}
 
+	if estimatedVal == 0 {
+		if lotValue, lotCurrency := tender.AggregateProcurementLotEstimatedValue(procurementLots); lotValue > 0 {
+			estimatedVal = lotValue
+			if currency == "" {
+				currency = lotCurrency
+			}
+		}
+	}
+
 	// Title and description stay in the notice language; English translation is handled by the AI service (translation worker).
 	t.Title = title
 	t.Description = description