fix loyalty points display

backend/src/main/java/com/petshop/backend/dto/sale/SaleResponse.java

@@ -20,6 +20,7 @@ public class SaleResponse {
     private BigDecimal employeeDiscountAmount;
     private BigDecimal loyaltyDiscountAmount;
     private Integer pointsEarned;
+    private Integer pointsUsed;
     private String channel;
     private Long couponId;
     private Long cartId;
@@ -145,6 +146,14 @@ public class SaleResponse {
         this.pointsEarned = pointsEarned;
     }
 
+    public Integer getPointsUsed() {
+        return pointsUsed;
+    }
+
+    public void setPointsUsed(Integer pointsUsed) {
+        this.pointsUsed = pointsUsed;
+    }
+
     public String getChannel() {
         return channel;
     }

backend/src/main/java/com/petshop/backend/entity/Sale.java

@@ -73,6 +73,9 @@ public class Sale {
     @Column(nullable = false)
     private Integer pointsEarned = 0;
 
+    @Column(nullable = false)
+    private Integer pointsUsed = 0;
+
     @OneToMany(mappedBy = "sale", cascade = CascadeType.ALL)
     private List<SaleItem> items = new ArrayList<>();
 
@@ -224,6 +227,14 @@ public class Sale {
         this.pointsEarned = pointsEarned;
     }
 
+    public Integer getPointsUsed() {
+        return pointsUsed;
+    }
+
+    public void setPointsUsed(Integer pointsUsed) {
+        this.pointsUsed = pointsUsed;
+    }
+
     public List<SaleItem> getItems() {
         return items;
     }

backend/src/main/java/com/petshop/backend/service/SaleService.java

@@ -200,6 +200,7 @@ public class SaleService {
             sale.setEmployeeDiscountAmount(BigDecimal.ZERO);
             sale.setLoyaltyDiscountAmount(loyaltyDiscountRefunded);
             sale.setPointsEarned(0);
+            sale.setPointsUsed(0);
         } else {
             if (request.getItems() == null || request.getItems().isEmpty()) {
                 throw new BusinessException("At least one item is required");
@@ -254,6 +255,7 @@ public class SaleService {
                 pointsDeducted = toPointsUsed(loyaltyDiscount);
             }
             sale.setLoyaltyDiscountAmount(loyaltyDiscount);
+            sale.setPointsUsed(pointsDeducted);
 
             BigDecimal finalTotal = subtotalAmount.subtract(couponDiscount).subtract(employeeDiscount).subtract(loyaltyDiscount);
             sale.setTotalAmount(finalTotal.max(BigDecimal.ZERO));
@@ -376,6 +378,7 @@ public class SaleService {
         response.setEmployeeDiscountAmount(sale.getEmployeeDiscountAmount());
         response.setLoyaltyDiscountAmount(sale.getLoyaltyDiscountAmount());
         response.setPointsEarned(sale.getPointsEarned());
+        response.setPointsUsed(sale.getPointsUsed());
         response.setChannel(sale.getChannel());
         if (sale.getCoupon() != null) {
             response.setCouponId(sale.getCoupon().getCouponId());