Send ETTN payment type and label explicitly, verify receipt total

Payments now carry type=ETTN / label=Експрес-накладна instead of relying on
Checkbox defaults; body build fails fast if goods - discounts - prepayment
does not equal the COD amount.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

backend/tests/test_receipts_service.py

@@ -108,7 +108,14 @@ class TestBuildBody:
                 "is_return": False,
             }
         ]
-        assert rb["payments"] == [{"value": 120000, "ettn": "20450123456789"}]
+        assert rb["payments"] == [
+            {
+                "type": "ETTN",
+                "label": "Експрес-накладна",
+                "value": 120000,
+                "ettn": "20450123456789",
+            }
+        ]
         assert "discounts" not in rb
         assert rb["delivery"] == {"phone": "+380501112233", "emails": ["a@b.ua"]}
 
@@ -131,6 +138,37 @@ class TestBuildBody:
         ]
         assert rb["payments"][0]["value"] == 85000
 
+    def test_all_goods_with_prices_quantities_and_sums(self) -> None:
+        order = _order(
+            goods=[
+                _good(id="1", sku="A", name="Сукня", price="600.00", amount="1200.00"),
+                _good(id="2", sku="", name="Пояс", price="150.50", quantity="1.000",
+                      amount="150.50"),
+                _good(id="3", sku="C", name="Тканина", price="99.99", quantity="1.500",
+                      amount="149.99"),
+            ],
+            total_amount_kopecks=150049,
+            np_cod_amount_kopecks=130049,  # 200 ₴ предоплаты
+        )
+        body = svc.build_ettn_body(order, _register(), svc.resolve_amounts(order, 20000))
+        rb = body["receipt_body"]
+
+        assert [
+            (g["good"]["code"], g["good"]["name"], g["good"]["price"], g["quantity"])
+            for g in rb["goods"]
+        ] == [
+            ("A", "Сукня", 60000, 2000),
+            ("2", "Пояс", 15050, 1000),  # пустой SKU → ID товара
+            ("C", "Тканина", 9999, 1500),
+        ]
+        # 99.99 × 1.5 = 149.985 → CRM округлила до 149.99, скидки по строке нет.
+        assert all("discounts" not in g for g in rb["goods"])
+        goods_total = sum(svc._line_sum(g["good"]["price"], g["quantity"]) for g in rb["goods"])
+        assert goods_total - 20000 == rb["payments"][0]["value"] == 130049
+        assert rb["discounts"] == [
+            {"type": "PRE_PAYMENT", "mode": "VALUE", "value": 20000, "name": "Передоплата"}
+        ]
+
     def test_fractional_quantity(self) -> None:
         order = _order(
             goods=[_good(price="100.00", quantity="2.250", amount="225.00")],