feat: 商品追踪页面 + 出库提交库存校验

后端：
- feat(backend): 重命名 Batches→Products 接口，新增库存状态(在售/已卖出)和买家信息
- feat(backend): 出库单创建/提交时校验仓库库存，不足则返回明确错误信息
- fix(backend): 出库创建 status 判断逻辑修复（空值默认 draft）

前端：
- feat(client): 批次追踪改为商品追踪，新增状态列(在售/已卖出)和买家/时间列
- fix(client): 无批次号时显示"无批次"而非空
- refactor(client): BatchRecord → ProductTrackingRecord，repository 接口更新

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/internal/handler/stock_out.go

@@ -1,6 +1,7 @@
 package handler
 
 import (
+	"fmt"
 	"net/http"
 	"strconv"
 
@@ -64,6 +65,31 @@ func (h *StockOutHandler) Get(c *gin.Context) {
 	c.JSON(http.StatusOK, gin.H{"data": order})
 }
 
+// checkInventory validates that warehouse has enough stock for each item.
+// warehouseID is the order's warehouse; items are the stock-out line items.
+func (h *StockOutHandler) checkInventory(shopID, warehouseID uint64, items []model.StockOutItem) error {
+	for _, item := range items {
+		var inv model.Inventory
+		err := h.db.Where("shop_id = ? AND warehouse_id = ? AND product_id = ?",
+			shopID, warehouseID, item.ProductID).First(&inv).Error
+		if err != nil || inv.Quantity < item.Quantity {
+			// Try to get product name for a clearer error message
+			var p model.Product
+			h.db.Where("id = ?", item.ProductID).First(&p)
+			name := p.Name
+			if name == "" {
+				name = fmt.Sprintf("商品ID %d", item.ProductID)
+			}
+			have := 0.0
+			if err == nil {
+				have = inv.Quantity
+			}
+			return fmt.Errorf("库存不足：%s 当前库存 %.0f，需要 %.0f", name, have, item.Quantity)
+		}
+	}
+	return nil
+}
+
 // Create POST /api/v1/stock-out/orders
 func (h *StockOutHandler) Create(c *gin.Context) {
 	shopID := middleware.GetShopID(c)
@@ -77,7 +103,16 @@ func (h *StockOutHandler) Create(c *gin.Context) {
 
 	req.ShopID = shopID
 	req.OperatorID = operatorID
-	req.Status = "draft"
+
+	// 状态只允许 draft 或 pending；直接提交审核时校验库存
+	if req.Status == "pending" {
+		if err := h.checkInventory(shopID, req.WarehouseID, req.Items); err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+			return
+		}
+	} else {
+		req.Status = "draft"
+	}
 
 	orderNo, err := h.stockSvc.GenerateOrderNo(shopID, "stock_out")
 	if err != nil {
@@ -104,13 +139,21 @@ func (h *StockOutHandler) Create(c *gin.Context) {
 // Submit PUT /api/v1/stock-out/orders/:id/submit
 func (h *StockOutHandler) Submit(c *gin.Context) {
 	shopID := middleware.GetShopID(c)
-	result := h.db.Model(&model.StockOutOrder{}).
+
+	// 加载订单及明细，校验库存后再改状态
+	var order model.StockOutOrder
+	if err := h.db.Preload("Items").
 		Where("id = ? AND shop_id = ? AND status = 'draft'", c.Param("id"), shopID).
-		Update("status", "pending")
-	if result.RowsAffected == 0 {
+		First(&order).Error; err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "order not found or not in draft status"})
 		return
 	}
+	if err := h.checkInventory(shopID, order.WarehouseID, order.Items); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	h.db.Model(&order).Update("status", "pending")
 	c.JSON(http.StatusOK, gin.H{"message": "submitted"})
 }