feat(distribution): 分站收号压价解耦买家价（方案 B 新口径）

核心语义反转：receive_cost_delta 为压价点数，收号比例 = 主站参考比例 R + 点数，
点数越大号主收号价越低；买家售价锚定主站参考比例推导，不再随收号价联动。

- 迁移 000072：distribution_sites 新增 receive_cost_delta（旧 receive_ratio_delta 保留只读）
- receive_pricing：新增 Normalize/ApplySiteReceiveCostDelta；分站定价买家侧改用
  R 锚点（referenceSellerCoinBasePrice），快照写入 site_receive_cost_delta 与 pricing_model 标记
- site_receive：新增 resolveSiteReceiveCostDelta 读取链路，旧 ResolveReceiveRatioDelta 保留
- 分成不变：压价差经结算层 profit 自动进入 35/40/25 三方分成池；
  货架自主加价仍 100% 归分站，两条边界均以主站为锚
- 权限对齐旧字段：主站全局管理员与分站操作员均可设置
- 前端三端同步：主站 pricing.ts/usePricingCalculator 买卖解耦试算、
  主站后台弹窗改「收号压价」价格语义文案、分销后台 SiteSettings 同步
- 测试：单测锚定 R=43 时 cost_delta=3 → 收号 217.4 / 卖价 263.2 不变 / markup 池 30.6→54.9

backend/internal/modules/listing/receive_pricing.go

@@ -36,7 +36,7 @@ func ReceivePricingFromAssetSummary(raw datatypes.JSON) ReceivePricingView {
 	}
 }
 
-func (s *Service) applyMainSiteReceivePricing(ctx context.Context, req *CreateRequest, receiveRatioDelta float64, onDistributionSite bool) error {
+func (s *Service) applyMainSiteReceivePricing(ctx context.Context, req *CreateRequest, receiveRatioDelta, receiveCostDelta float64, onDistributionSite bool) error {
 	if req == nil {
 		return nil
 	}
@@ -48,11 +48,12 @@ func (s *Service) applyMainSiteReceivePricing(ctx context.Context, req *CreateRe
 	if err != nil {
 		return err
 	}
-	applyMainSiteReceivePricing(req, options, config, receiveRatioDelta, onDistributionSite)
+	applyMainSiteReceivePricing(req, options, config, receiveRatioDelta, receiveCostDelta, onDistributionSite)
 	return nil
 }
 
-func applyMainSiteReceivePricing(req *CreateRequest, options systemconfig.PublishOptionsDTO, config salePriceConfig, receiveRatioDelta float64, onDistributionSite bool) {
+func applyMainSiteReceivePricing(req *CreateRequest, options systemconfig.PublishOptionsDTO, config salePriceConfig, receiveRatioDelta, receiveCostDelta float64, onDistributionSite bool) {
+
 	if req == nil {
 		return
 	}
@@ -70,18 +71,20 @@ func applyMainSiteReceivePricing(req *CreateRequest, options systemconfig.Publis
 	if requestedRatio <= 0 {
 		requestedRatio = readSummaryNumber(breakdown["accelerated_sale_ratio"])
 	}
+	costDelta := NormalizeSiteReceiveCostDelta(receiveCostDelta)
+	ratioDelta := NormalizeSiteReceiveRatioDelta(receiveRatioDelta)
 	sellerRatio := clampSaleRatio(referenceRatio, requestedRatio)
-	delta := NormalizeSiteReceiveRatioDelta(receiveRatioDelta)
+	// 分站新口径：收号比例 = R + 压价点数（收号价更低），买家定价锚定主站参考比例 R，不随收号价联动。
 	if onDistributionSite {
-		sellerRatio = ApplySiteReceiveRatioDelta(referenceRatio, delta)
+		sellerRatio = ApplySiteReceiveCostDelta(referenceRatio, costDelta)
 	}
 	coinWan := coinM * 100
 	sellerCoinBasePrice := roundMoney(coinWan / sellerRatio)
 	consumablePrice := consumableValue(req.AssetSummary)
 	sellerTotalPrice := roundMoney(sellerCoinBasePrice + consumablePrice)
 	dailyLoss := readSummaryNumber(req.AssetSummary["daily_loss_m"])
-	pricing := calculateExternalPlatformPricing(coinM, sellerRatio, sellerCoinBasePrice, consumablePrice, config)
-
+	// 买家价始终按主站口径推导：分站只改收号侧，卖价与主站同基准（压价差进入三方分成池）。
+	pricing := calculateExternalPlatformPricing(coinM, referenceRatio, referenceSellerCoinBasePrice(coinWan, referenceRatio), consumablePrice, config)
 	breakdown["seller_reference_ratio"] = referenceRatio
 	breakdown["seller_ratio"] = sellerRatio
 	breakdown["seller_coin_base_price"] = sellerCoinBasePrice
@@ -89,7 +92,12 @@ func applyMainSiteReceivePricing(req *CreateRequest, options systemconfig.Publis
 	breakdown["consumable_price"] = consumablePrice
 	breakdown["daily_loss_ratio_adjustment"] = calculateDailyLossRatioAdjustment(dailyLoss)
 	breakdown["accelerated_sale_ratio"] = sellerRatio
-	breakdown["site_receive_ratio_delta"] = delta
+	if onDistributionSite {
+		breakdown["site_receive_cost_delta"] = costDelta
+		breakdown["pricing_model"] = "site_cost_decoupled_v1"
+	} else {
+		breakdown["site_receive_ratio_delta"] = ratioDelta
+	}
 	breakdown["buyer_coin_base_price"] = pricing.BuyerCoinBasePrice
 	breakdown["buyer_total_price"] = pricing.BuyerTotalPrice
 	breakdown["buyer_ratio"] = pricing.BuyerRatio
@@ -100,6 +108,36 @@ func applyMainSiteReceivePricing(req *CreateRequest, options systemconfig.Publis
 	req.PriceCent = yuanToCent(pricing.BuyerTotalPrice)
 }
 
+// NormalizeSiteReceiveCostDelta 将分站收号压价点数限制在 [0, 20]。
+// 点数越大，分站收号比例越高（相对主站参考比例），收号价越低；0 表示与主站同价收号。
+func NormalizeSiteReceiveCostDelta(delta float64) float64 {
+	if delta < 0 || math.IsNaN(delta) || math.IsInf(delta, 0) {
+		return 0
+	}
+	if delta > maxSiteReceiveRatioDelta {
+		return maxSiteReceiveRatioDelta
+	}
+	return roundRatio(delta)
+}
+
+// ApplySiteReceiveCostDelta 按新口径计算分站收号比例：R + 压价点数（收号价更低）。
+// 与旧 ApplySiteReceiveRatioDelta 相反方向，买家价已解耦、不再从收号比例推导。
+func ApplySiteReceiveCostDelta(referenceRatio, delta float64) float64 {
+	if referenceRatio <= 0 {
+		return 0
+	}
+	siteRatio := roundRatio(referenceRatio + NormalizeSiteReceiveCostDelta(delta))
+	return siteRatio
+}
+
+// referenceSellerCoinBasePrice 计算主站参考比例下的号主基础价，用作买家定价锚点。
+func referenceSellerCoinBasePrice(coinWan, referenceRatio float64) float64 {
+	if referenceRatio <= 0 {
+		return 0
+	}
+	return roundMoney(coinWan / referenceRatio)
+}
+
 // NormalizeSiteReceiveRatioDelta 将分站收号下调点数限制在 [0, 20]。
 func NormalizeSiteReceiveRatioDelta(delta float64) float64 {
 	if delta < 0 || math.IsNaN(delta) || math.IsInf(delta, 0) {