feat: 自动更新、系统设置、安全修复

后端：
- 新增 GET /version 版本检查端点（version.go + version.yaml）
- 新增 GET /license/info 接口，返回门店授权信息
- 修复 GenerateOrderNo 并发重复单号：事务内加 FOR UPDATE 行锁
- 修复 ApproveStockOut 超卖竞态：预检和库存更新均加 FOR UPDATE
- 修复 Product Create 并发 code 冲突：加重试逻辑，schema 加 UNIQUE KEY
- 修复 Product Update 全字段覆盖：改用 selective Updates()
- 挂载 ReadOnly 中间件（全局）+ AdminOnly（用户管理路由）
- version.go 配置缺失时返回 500 而非静默降级

前端：
- 新增自动更新检测（update_provider.dart）+ shell 更新 banner/弹窗
- 新增系统设置"关于"标签页：版本、授权、开发信息、意见反馈
- 新增离线缓存：所有 AsyncNotifierProvider 支持断网浏览历史数据
- 新增门店信息弹窗（点击左上角 logo 或右上角门店号触发）
- 提取 AppConfig 统一管理 BASE_URL，支持 --dart-define 注入
- update_provider.dart 加 kIsWeb 保护，修复 Web 平台崩溃
- dev.sh 新增 stop 命令，修复 stop 误杀前端进程问题

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

backend/internal/handler/stock_in.go

@@ -1,6 +1,7 @@
 package handler
 
 import (
+	"fmt"
 	"net/http"
 	"strconv"
 	"time"
@@ -93,12 +94,15 @@ func (h *StockInHandler) Create(c *gin.Context) {
 	}
 	req.OrderNo = orderNo
 
-	// 计算总金额
+	// 计算总金额；自动生成批次号
 	var total float64
 	for i := range req.Items {
 		req.Items[i].ShopID = shopID
 		req.Items[i].TotalPrice = req.Items[i].Quantity * req.Items[i].UnitPrice
 		total += req.Items[i].TotalPrice
+		if req.Items[i].BatchNo == "" {
+			req.Items[i].BatchNo = fmt.Sprintf("%s-%02d", req.OrderNo, i+1)
+		}
 	}
 	req.TotalAmount = total
 
@@ -109,6 +113,75 @@ func (h *StockInHandler) Create(c *gin.Context) {
 	c.JSON(http.StatusCreated, gin.H{"data": req})
 }
 
+// Update PUT /api/v1/stock-in/orders/:id （只允许草稿状态）
+func (h *StockInHandler) Update(c *gin.Context) {
+	shopID := middleware.GetShopID(c)
+
+	var order model.StockInOrder
+	if err := h.db.Where("id = ? AND shop_id = ? AND status = 'draft' AND deleted_at IS NULL", c.Param("id"), shopID).
+		First(&order).Error; err != nil {
+		c.JSON(http.StatusNotFound, gin.H{"error": "入库单不存在或不可修改"})
+		return
+	}
+
+	var req model.StockInOrder
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	err := h.db.Transaction(func(tx *gorm.DB) error {
+		if err := tx.Where("order_id = ?", order.ID).Delete(&model.StockInItem{}).Error; err != nil {
+			return err
+		}
+		var total float64
+		for i := range req.Items {
+			req.Items[i].ShopID = shopID
+			req.Items[i].OrderID = order.ID
+			req.Items[i].TotalPrice = req.Items[i].Quantity * req.Items[i].UnitPrice
+			total += req.Items[i].TotalPrice
+			if req.Items[i].BatchNo == "" {
+				req.Items[i].BatchNo = fmt.Sprintf("%s-%02d", order.OrderNo, i+1)
+			}
+		}
+		updates := map[string]interface{}{
+			"warehouse_id": req.WarehouseID,
+			"partner_id":   req.PartnerID,
+			"order_date":   req.OrderDate,
+			"remark":       req.Remark,
+			"total_amount": total,
+		}
+		if err := tx.Model(&order).Updates(updates).Error; err != nil {
+			return err
+		}
+		if len(req.Items) > 0 {
+			if err := tx.Create(&req.Items).Error; err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"message": "updated"})
+}
+
+// Delete DELETE /api/v1/stock-in/orders/:id （只允许草稿状态）
+func (h *StockInHandler) Delete(c *gin.Context) {
+	shopID := middleware.GetShopID(c)
+	now := timeNow()
+	result := h.db.Model(&model.StockInOrder{}).
+		Where("id = ? AND shop_id = ? AND status = 'draft' AND deleted_at IS NULL", c.Param("id"), shopID).
+		Update("deleted_at", now)
+	if result.RowsAffected == 0 {
+		c.JSON(http.StatusNotFound, gin.H{"error": "入库单不存在或不可删除"})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"message": "deleted"})
+}
+
 // Submit PUT /api/v1/stock-in/orders/:id/submit （草稿→待审核）
 func (h *StockInHandler) Submit(c *gin.Context) {
 	shopID := middleware.GetShopID(c)