fix(fifo): ContentBasedDeduplication + dedup window survives delete (AWS semantics)

- ContentBasedDeduplication=true: dedupId computed from body SHA-256 when not provided
- do NOT drop dedupId on message delete: AWS keeps the 5-minute window regardless
  (previously re-send after delete delivered the message again)
- utils: GetSHA256Hash

app/gosqs/delete_message_batch.go

@@ -93,10 +93,10 @@ func DeleteMessageBatchV1(req *http.Request) (int, interfaces.AbstractResponseBo
 		}
 		log.Debugf("FIFO Queue %s unlocking group %s:", queueName, message.GroupID)
 		// Читаем поля ДО RemoveIndex: компакция может перезаписать слот.
-		groupID, dedupID, uuid := message.GroupID, message.DeduplicationID, message.Uuid
+		groupID, uuid := message.GroupID, message.Uuid
 		queue.ClearInFlight(i, message.ReceiptHandle)
 		queue.UnlockGroup(groupID)
-		delete(queue.Duplicates, dedupID)
+		// Duplicates НЕ чистим — dedup-окно 5 минут живёт независимо от удаления (AWS).
 		de.Deleted = true
 		deletedEntries = append(deletedEntries, models.DeleteMessageBatchResultEntry{Id: de.Id})
 		deletedUuids = append(deletedUuids, uuid)