fix(distribution): 分成改为分主站提价利润，分站自主提价溢价全额归卖方

- 文档：升级至 v0.7，固化号主保底、主站提价利润分账（35/40/25）与分站加价溢价独享逻辑
- 定价：修正货架兑换比例调价方向为调减比例提价（site_ratio = base_ratio - delta）
- 分账：分成基数剔除号主成本与分站加价，提价利润按规则切分，分站自主加价溢价 100% 归卖出方
- 前端：更新分销后台提价说明文案，提示调减比例提高售价且溢价归本站

backend/internal/modules/distribution/pricing.go

@@ -146,7 +146,7 @@ func CalculateSettlement(rule Rule, input SettlementInput) (SettlementResult, er
 	}
 	netPaid := input.GrossPaidAmountCent - input.RefundAmountCent
 	paymentFee := roundHalfUp(float64(netPaid) * float64(rule.PaymentFeeBPS) / 10000)
-	profit := netPaid - input.OwnerRentAmountCent - paymentFee
+	profit := netPaid - input.OwnerRentAmountCent - input.MarkupAmountCent - paymentFee
 	if profit < 0 {
 		profit = 0
 	}
@@ -212,8 +212,9 @@ type PartySplit struct {
 	AmountCent int64
 }
 
-// SplitSettlement 按百分数切利润：收号 35%、卖出 40%。服务费 25% 记在财务快照，不并进参与方。
-func SplitSettlement(rule Rule, profitCent int64) []PartySplit {
+// SplitSettlement 按百分数切主站提价利润（收号 35%、卖出 40%），并将分站自主加价溢价（markupCent）100% 独立全额归入卖出方。
+// 平台服务费 25% 记在财务快照，不并进参与方。
+func SplitSettlement(rule Rule, profitCent int64, markupCent int64) []PartySplit {
 	roles := []struct {
 		role  string
 		ratio float64
@@ -242,19 +243,34 @@ func SplitSettlement(rule Rule, profitCent int64) []PartySplit {
 		amount := roundHalfUp(float64(profitCent) * item.ratio / 100)
 		splits = append(splits, PartySplit{PartyRole: item.role, Ratio: item.ratio, AmountCent: maxInt64(amount, 0)})
 	}
+	if markupCent > 0 {
+		sellerRole := "distributor_sell"
+		switch rule.Mode {
+		case ModeTwoPartyDistributorReceive:
+			sellerRole = "platform_sell"
+		case ModeThreeParty:
+			sellerRole = "distributor_b"
+		}
+		for i := range splits {
+			if splits[i].PartyRole == sellerRole {
+				splits[i].AmountCent += markupCent
+			}
+		}
+	}
 	return splits
 }
 
-// SplitRemainderCent 返回利润扣除各方分成后的剩余（未扣服务费）。
-func SplitRemainderCent(splitBase int64, splits []PartySplit) int64 {
+// SplitRemainderCent 返回主站提价利润扣除各方提价分成后的剩余（未扣服务费）。
+func SplitRemainderCent(splitBase int64, splits []PartySplit, markupCent int64) int64 {
 	sum := int64(0)
 	for _, item := range splits {
 		sum += item.AmountCent
 	}
-	return splitBase - sum
+	profitSplitSum := sum - markupCent
+	return splitBase - profitSplitSum
 }
 
-// SplitRoundingCent 返回利润扣完收号、卖出和服务费后的四舍五入尾差。
-func SplitRoundingCent(profitCent, serviceFeeCent int64, splits []PartySplit) int64 {
-	return SplitRemainderCent(profitCent, splits) - serviceFeeCent
+// SplitRoundingCent 返回提价利润扣完收号、卖出和服务费后的四舍五入尾差。
+func SplitRoundingCent(profitCent, serviceFeeCent, markupCent int64, splits []PartySplit) int64 {
+	return SplitRemainderCent(profitCent, splits, markupCent) - serviceFeeCent
 }