fix(payments): stop doubling the pack size in buyer mail

Catalog titles already name the pack ("50 фишек"), so appending the chip count
produced "50 фишек — 50 фишек, 79.00 ₽". The letter now carries the title
exactly as the storefront shows it, then the price.

The tax receipt is unaffected: it states the quantity in the wording the tax
service wants, which is a separate surface with separate requirements.

backend/internal/inttest/mynalog_test.go

@@ -661,6 +661,11 @@ func TestMyNalogBuyerMails(t *testing.T) {
 	if !strings.Contains(first[0].Text, "не чек") {
 		t.Errorf("the purchase letter does not say it is not the receipt:\n%s", first[0].Text)
 	}
+	// The catalog title already names the pack size, so appending it again read as
+	// "50 фишек — 50 фишек". The line is the title verbatim, then the price, and nothing else.
+	if !strings.Contains(first[0].Text, "Покупка совершена: test pack, 149.00 ₽.") {
+		t.Errorf("the purchase line is not the catalog title plus the price:\n%s", first[0].Text)
+	}
 
 	// 2. The receipt letter, once the income is filed, carrying the printable link.
 	if _, err := exp.RunBatch(ctx, time.Minute); err != nil {

backend/internal/mynalogsync/mailer.go

@@ -185,15 +185,18 @@ func (m *Mailer) stampReceipt(ctx context.Context, mark func(context.Context, uu
 	}
 }
 
-// describe renders what was bought in one line.
+// describe renders what was bought in one line: the catalog title exactly as the buyer saw it on
-func describe(title string, chips int, amountMinor int64, currency string) string {
+// the storefront, then the price.
+//
+// The pack size is deliberately NOT appended. Catalog titles already name it ("50 фишек"), so
+// adding it produced "50 фишек — 50 фишек". The title is the single source of that wording; the
+// tax receipt states the quantity separately in the form the tax service wants (see
+// mynalog.IncomeName), which is a different surface with different requirements.
+func describe(title string, amountMinor int64, currency string) string {
 	what := strings.TrimSpace(title)
 	if what == "" {
 		what = "покупка в игре"
 	}
-	if chips > 0 {
-		what = fmt.Sprintf("%s — %d фишек", what, chips)
-	}
 	return fmt.Sprintf("%s, %s", what, formatAmount(amountMinor, currency))
 }
 
@@ -224,7 +227,7 @@ func purchaseText(p payments.PurchaseMail) string {
 отдельным письмом: обычно в течение часа, но иногда это занимает до нескольких дней.
 
 Спасибо, что играете в «Эрудит».
-`, describe(p.Title, p.Chips, p.AmountMinor, p.Currency), p.OrderID)
+`, describe(p.Title, p.AmountMinor, p.Currency), p.OrderID)
 }
 
 // receiptText is the fiscal receipt letter, which is how the receipt is actually handed to the
@@ -240,7 +243,7 @@ func receiptText(r payments.ReceiptMail, inn, baseURL string, loc *time.Location
 
 Продавец применяет налог на профессиональный доход; чек сформирован в сервисе
 «Мой налог» Федеральной налоговой службы.
-`, describe(r.Title, r.Chips, r.AmountMinor, r.Currency),
+`, describe(r.Title, r.AmountMinor, r.Currency),
 		r.OperationTime.In(loc).Format("02.01.2006 15:04"),
 		mynalog.ReceiptURL(baseURL, inn, r.ReceiptUUID))
 }
@@ -255,6 +258,6 @@ func cancelText(r payments.ReceiptMail, loc *time.Location) string {
 
 %s
 Дата покупки: %s
-`, describe(r.Title, r.Chips, r.AmountMinor, r.Currency),
+`, describe(r.Title, r.AmountMinor, r.Currency),
 		r.OperationTime.In(loc).Format("02.01.2006 15:04"))
 }

backend/internal/payments/mynalog.go

@@ -125,7 +125,6 @@ type PurchaseMail struct {
 	OrderID     uuid.UUID
 	Origin      string
 	Title       string
-	Chips       int
 	AmountMinor int64
 	Currency    string
 	CreatedAt   time.Time
@@ -137,7 +136,6 @@ type ReceiptMail struct {
 	AccountID     uuid.UUID
 	ReceiptUUID   string
 	Title         string
-	Chips         int
 	AmountMinor   int64
 	Currency      string
 	OperationTime time.Time

backend/internal/payments/store_mynalog.go

@@ -476,7 +476,7 @@ func (s *Store) pendingPurchaseMails(ctx context.Context, limit int) ([]Purchase
 	rows, err := s.db.QueryContext(ctx, `
 		SELECT e.event_id, e.account_id, e.order_id, COALESCE(o.origin, ''),
 		       COALESCE(o.expected_amount, 0), COALESCE(o.currency, ''),
-		       COALESCE(p.title, ''), COALESCE((e.payload->>'chips')::int, 0), e.created_at
+		       COALESCE(p.title, ''), e.created_at
 		FROM payments.payment_events e
 		LEFT JOIN payments.orders o ON o.order_id = e.order_id
 		LEFT JOIN payments.product p ON p.product_id = o.product_id
@@ -495,7 +495,7 @@ func (s *Store) pendingPurchaseMails(ctx context.Context, limit int) ([]Purchase
 			orderID uuid.NullUUID
 		)
 		if err := rows.Scan(&m.EventID, &m.AccountID, &orderID, &m.Origin, &m.AmountMinor,
-			&m.Currency, &m.Title, &m.Chips, &m.CreatedAt); err != nil {
+			&m.Currency, &m.Title, &m.CreatedAt); err != nil {
 			return nil, fmt.Errorf("payments: scan purchase mail: %w", err)
 		}
 		m.OrderID = orderID.UUID
@@ -551,7 +551,7 @@ func (s *Store) pendingMyNalogMails(ctx context.Context, limit int, cancelled bo
 			&m.AmountMinor, &m.Currency, &m.OperationTime); err != nil {
 			return nil, fmt.Errorf("payments: scan receipt mail: %w", err)
 		}
-		m.Title, m.Chips = describeSnapshot(snapshot.String)
+		m.Title, _ = describeSnapshot(snapshot.String)
 		out = append(out, m)
 	}
 	if err := rows.Err(); err != nil {