feat(backend): 出入库定价字段消歧 + 总利润落库 + 成本仅管理员可见

- 字段重命名（旧列弃用保留，启动幂等回填 BackfillPricingColumns）：
  入库 unit_price/total_price/total_amount → cost_price/cost_amount/cost_total；
  出库同前缀 + 新增 sale_amount（售价小计）/ sale_total（应收）/ profit_total（总利润）
- 建单落三值；确认售价联动重算 sale_amount/sale_total/profit_total；
  确认进价回填成本后联动重算受影响出库单利润（recalcStockOutProfit）
- 出库 List/Get 对 operator/readonly 抹零成本与利润（stripStockOutCost 服务端兜底）
- 兼容一版：Create/Update 接受旧 key unit_price 回落（v1.0.87 及之前客户端）
- SUM 聚合/价格趋势/导入/种子工具同步切新列；测试全量改名 + 6 个新回归

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JJ1g8XV1YhhmHRzhwWEW7o

backend/internal/handler/stock_in.go

@@ -193,7 +193,7 @@ func (h *StockInHandler) Summary(c *gin.Context) {
 		}
 		h.db.Model(&model.StockInOrder{}).
 			Where("shop_id = ? AND deleted_at IS NULL AND order_date >= ? AND order_date < ?", shopID, from, to).
-			Select("COUNT(*) AS cnt, COALESCE(SUM(total_amount),0) AS amt").Scan(&r)
+			Select("COUNT(*) AS cnt, COALESCE(SUM(cost_total),0) AS amt").Scan(&r)
 		return r.Cnt, r.Amt
 	}
 	var s stockSummary
@@ -258,19 +258,23 @@ func (h *StockInHandler) Create(c *gin.Context) {
 		for i := range req.Items {
 			it := &req.Items[i]
 			it.ShopID = shopID
+			// 兼容旧客户端(≤1.0.87)：unit_price 回落为 cost_price（新 key 优先）
+			if it.CostPrice == 0 && it.LegacyUnitPrice != nil {
+				it.CostPrice = *it.LegacyUnitPrice
+			}
 			if it.BatchNo == "" {
 				it.BatchNo = fmt.Sprintf("%s-%02d", req.OrderNo, i+1)
 			}
-			prod, e := createIndependentProduct(tx, shopID, it.ProductName, it.Series, it.Spec, it.BatchNo, it.ProductionDate, it.UnitPrice, it.SalePrice)
+			prod, e := createIndependentProduct(tx, shopID, it.ProductName, it.Series, it.Spec, it.BatchNo, it.ProductionDate, it.CostPrice, it.SalePrice)
 			if e != nil {
 				return e
 			}
 			it.ProductID = prod.ID
 			it.ProductCode = prod.Code // 保留快照,兼容现有查询(瘦身阶段再去)
-			it.TotalPrice = it.Quantity * it.UnitPrice
-			total += it.TotalPrice
+			it.CostAmount = it.Quantity * it.CostPrice
+			total += it.CostAmount
 		}
-		req.TotalAmount = total
+		req.CostTotal = total
 		return tx.Create(&req).Error
 	})
 	if err != nil {
@@ -316,25 +320,28 @@ func (h *StockInHandler) Update(c *gin.Context) {
 			it := &req.Items[i]
 			it.ShopID = shopID
 			it.OrderID = order.ID
+			if it.CostPrice == 0 && it.LegacyUnitPrice != nil {
+				it.CostPrice = *it.LegacyUnitPrice
+			}
 			if it.BatchNo == "" {
 				it.BatchNo = fmt.Sprintf("%s-%02d", order.OrderNo, i+1)
 			}
 			// 编辑草稿:旧明细已删,每条按新模型重建独立产品（旧草稿 product 无库存,暂留待后续清理）
-			prod, e := createIndependentProduct(tx, shopID, it.ProductName, it.Series, it.Spec, it.BatchNo, it.ProductionDate, it.UnitPrice, it.SalePrice)
+			prod, e := createIndependentProduct(tx, shopID, it.ProductName, it.Series, it.Spec, it.BatchNo, it.ProductionDate, it.CostPrice, it.SalePrice)
 			if e != nil {
 				return e
 			}
 			it.ProductID = prod.ID
 			it.ProductCode = prod.Code
-			it.TotalPrice = it.Quantity * it.UnitPrice
-			total += it.TotalPrice
+			it.CostAmount = it.Quantity * it.CostPrice
+			total += it.CostAmount
 		}
 		updates := map[string]interface{}{
 			"warehouse_id": req.WarehouseID,
 			"partner_id":   req.PartnerID,
 			"order_date":   req.OrderDate,
 			"remark":       req.Remark,
-			"total_amount": total,
+			"cost_total": total,
 		}
 		if err := tx.Model(&order).Updates(updates).Error; err != nil {
 			return err