修复(#79): 促销管理后台API + 审查问题修复

- 实现促销管理接口：规则CRUD、优惠价配置、使用记录查询
- 修复 UpsertPrices 新增记录时提前 return 的问题
- DeleteRule/DeletePrice 不存在记录返回 code=404
- SetPromoPriceRequest.items 空数组校验
- 分页参数限制 page>0、1<=size<=200
- 下单侧促销价格按数量档总价口径计算（含 #87 修复）

Co-authored-by: multica-agent <github@multica.ai>

internal/logic/public/order/promoPricing_test.go

@@ -31,7 +31,51 @@ func (m *fakePromoModel) InsertUsage(context.Context, *promo.Usage, ...*gorm.DB)
 	return nil
 }
 
-func TestCalculatePurchasePricePromoSkipsPercentDiscount(t *testing.T) {
+func (m *fakePromoModel) InsertRule(context.Context, *promo.Rule) error {
+	return nil
+}
+
+func (m *fakePromoModel) FindRule(context.Context, int64) (*promo.Rule, error) {
+	return nil, gorm.ErrRecordNotFound
+}
+
+func (m *fakePromoModel) UpdateRule(context.Context, *promo.Rule) error {
+	return nil
+}
+
+func (m *fakePromoModel) DeleteRule(context.Context, int64) error {
+	return nil
+}
+
+func (m *fakePromoModel) QueryRuleList(context.Context, int, int, string, *bool, string) (int64, []*promo.Rule, error) {
+	return 0, nil, nil
+}
+
+func (m *fakePromoModel) UpsertPrices(context.Context, int64, []*promo.SubscribePromo) error {
+	return nil
+}
+
+func (m *fakePromoModel) FindPrice(context.Context, int64) (*promo.SubscribePromo, error) {
+	return nil, gorm.ErrRecordNotFound
+}
+
+func (m *fakePromoModel) DeletePrice(context.Context, int64) error {
+	return nil
+}
+
+func (m *fakePromoModel) QueryPriceList(context.Context, int64, int, int) (int64, []*promo.SubscribePromo, error) {
+	return 0, nil, nil
+}
+
+func (m *fakePromoModel) QueryUsageList(context.Context, promo.UsageFilter) (int64, []*promo.Usage, error) {
+	return 0, nil, nil
+}
+
+func (m *fakePromoModel) Transaction(context.Context, func(*gorm.DB) error) error {
+	return nil
+}
+
+func TestCalculatePurchasePricePromoUsesQuantityTierTotalPrice(t *testing.T) {
 	model := &fakePromoModel{rules: []*promo.RuleWithPrice{
 		{
 			Rule: promo.Rule{
@@ -40,7 +84,7 @@ func TestCalculatePurchasePricePromoSkipsPercentDiscount(t *testing.T) {
 				Type:    promo.RuleTypeCampaign,
 				Enabled: true,
 			},
-			PromoPrice: 600,
+			PromoPrice: 279,
 		},
 	}}
 	svcCtx := &svc.ServiceContext{
@@ -53,9 +97,9 @@ func TestCalculatePurchasePricePromoSkipsPercentDiscount(t *testing.T) {
 		svcCtx,
 		1,
 		2,
-		1000,
-		3,
-		[]types.SubscribeDiscount{{Quantity: 3, Discount: 50}},
+		100,
+		7,
+		[]types.SubscribeDiscount{{Quantity: 7, Discount: 50}},
 		true,
 		true,
 	)
@@ -63,11 +107,11 @@ func TestCalculatePurchasePricePromoSkipsPercentDiscount(t *testing.T) {
 		t.Fatalf("calculatePurchasePrice returned error: %v", err)
 	}
 
-	if result.OriginalPrice != 3000 {
-		t.Fatalf("OriginalPrice = %d, want 3000", result.OriginalPrice)
+	if result.OriginalPrice != 700 {
+		t.Fatalf("OriginalPrice = %d, want 700", result.OriginalPrice)
 	}
-	if result.PayableBase != 1800 {
-		t.Fatalf("PayableBase = %d, want 1800", result.PayableBase)
+	if result.PayableBase != 279 {
+		t.Fatalf("PayableBase = %d, want 279", result.PayableBase)
 	}
 	if result.DiscountAmount != 0 {
 		t.Fatalf("DiscountAmount = %d, want 0", result.DiscountAmount)
@@ -75,11 +119,14 @@ func TestCalculatePurchasePricePromoSkipsPercentDiscount(t *testing.T) {
 	if result.PromoRuleId != 9 {
 		t.Fatalf("PromoRuleId = %d, want 9", result.PromoRuleId)
 	}
-	if result.PromoDiscount != 1200 {
-		t.Fatalf("PromoDiscount = %d, want 1200", result.PromoDiscount)
+	if result.PromoDiscount != 421 {
+		t.Fatalf("PromoDiscount = %d, want 421", result.PromoDiscount)
 	}
-	if model.lastQuantity != 3 {
-		t.Fatalf("promo query quantity = %d, want 3", model.lastQuantity)
+	if result.PromoPrice != 279 {
+		t.Fatalf("PromoPrice = %d, want 279", result.PromoPrice)
+	}
+	if model.lastQuantity != 7 {
+		t.Fatalf("promo query quantity = %d, want 7", model.lastQuantity)
 	}
 }
 
@@ -92,7 +139,7 @@ func TestCalculatePurchasePriceIgnoresInvalidPromoPrice(t *testing.T) {
 				Type:    promo.RuleTypeCampaign,
 				Enabled: true,
 			},
-			PromoPrice: 1000,
+			PromoPrice: 3000,
 		},
 	}}
 	svcCtx := &svc.ServiceContext{
@@ -137,7 +184,7 @@ func TestCalculatePurchasePricePassesQuantityToPromoEvaluation(t *testing.T) {
 					Type:    promo.RuleTypeCampaign,
 					Enabled: true,
 				},
-				PromoPrice: 500,
+				PromoPrice: 3000,
 			},
 		},
 	}