feat: 入库单/商品详情展示产地保质期储存方式，商品详情显示建议零售价

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

backend/internal/handler/product.go

@@ -165,6 +165,7 @@ func (h *ProductHandler) Detail(c *gin.Context) {
 	var product model.Product
 	if err := h.db.Where("id = ? AND shop_id = ? AND deleted_at IS NULL", id, shopID).
 		Preload("Category").Preload("Images").
+		Preload("Origin").Preload("ShelfLife").Preload("Storage").
 		First(&product).Error; err != nil {
 		c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
 		return

backend/internal/handler/stock_in.go

@@ -62,7 +62,9 @@ func (h *StockInHandler) List(c *gin.Context) {
 func (h *StockInHandler) Get(c *gin.Context) {
 	shopID := middleware.GetShopID(c)
 	var order model.StockInOrder
-	if err := h.db.Preload("Items.Product").Preload("Warehouse").Preload("Partner").Preload("Operator").Preload("Reviewer").
+	if err := h.db.Preload("Items.Product").Preload("Items.Product.Origin").
+		Preload("Items.Product.ShelfLife").Preload("Items.Product.Storage").
+		Preload("Warehouse").Preload("Partner").Preload("Operator").Preload("Reviewer").
 		Where("id = ? AND shop_id = ? AND deleted_at IS NULL", c.Param("id"), shopID).
 		First(&order).Error; err != nil {
 		c.JSON(http.StatusNotFound, gin.H{"error": "not found"})