init: 后端框架脚手架 (Go + Gin + GORM + MySQL)

- 项目目录结构：backend/ deploy/ schema/ migrations/
- 数据库 Schema：所有建表 SQL，含 hotel_id 多租户隔离
- Go 后端：config、model、handler、service、middleware、router
- 认证：账号密码登录 + JWT（Access + Refresh Token）
- 许可证：HMAC-SHA256 激活码生成 + 设备绑定验证
- 业务模块：商品、仓库、往来单位、入库、出库、库存、盘点
- 库存事务：入库/出库审核时原子更新库存 + 流水记录
- 数据导入：Excel/CSV 批量导入商品、往来单位
- Docker Compose：本地 MySQL + Adminer

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

backend/internal/handler/inventory.go

@@ -0,0 +1,116 @@
+package handler
+
+import (
+	"net/http"
+	"strconv"
+
+	"github.com/gin-gonic/gin"
+	"gorm.io/gorm"
+
+	"github.com/wangjia/jiu/backend/internal/middleware"
+	"github.com/wangjia/jiu/backend/internal/model"
+)
+
+type InventoryHandler struct {
+	db *gorm.DB
+}
+
+func NewInventoryHandler(db *gorm.DB) *InventoryHandler {
+	return &InventoryHandler{db: db}
+}
+
+// List GET /api/v1/inventory
+func (h *InventoryHandler) List(c *gin.Context) {
+	hotelID := middleware.GetHotelID(c)
+	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))
+
+	query := h.db.Model(&model.Inventory{}).Where("hotel_id = ?", hotelID)
+
+	if warehouseID := c.Query("warehouse_id"); warehouseID != "" {
+		query = query.Where("warehouse_id = ?", warehouseID)
+	}
+	if productID := c.Query("product_id"); productID != "" {
+		query = query.Where("product_id = ?", productID)
+	}
+	// 仅显示有库存
+	if c.Query("in_stock") == "1" {
+		query = query.Where("quantity > 0")
+	}
+
+	var total int64
+	query.Count(&total)
+
+	var inventory []model.Inventory
+	query.Preload("Product").Preload("Warehouse").
+		Offset((page - 1) * pageSize).Limit(pageSize).
+		Find(&inventory)
+
+	c.JSON(http.StatusOK, gin.H{"data": inventory, "total": total, "page": page, "page_size": pageSize})
+}
+
+// Logs GET /api/v1/inventory/logs
+func (h *InventoryHandler) Logs(c *gin.Context) {
+	hotelID := middleware.GetHotelID(c)
+	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))
+
+	query := h.db.Model(&model.InventoryLog{}).Where("hotel_id = ?", hotelID)
+
+	if productID := c.Query("product_id"); productID != "" {
+		query = query.Where("product_id = ?", productID)
+	}
+
+	var total int64
+	query.Count(&total)
+
+	var logs []model.InventoryLog
+	query.Offset((page - 1) * pageSize).Limit(pageSize).Order("id DESC").Find(&logs)
+
+	c.JSON(http.StatusOK, gin.H{"data": logs, "total": total, "page": page, "page_size": pageSize})
+}
+
+// CreateCheck POST /api/v1/inventory/checks
+func (h *InventoryHandler) CreateCheck(c *gin.Context) {
+	hotelID := middleware.GetHotelID(c)
+	operatorID := middleware.GetUserID(c)
+
+	var req model.InventoryCheck
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	req.HotelID = hotelID
+	req.OperatorID = operatorID
+	req.Status = "draft"
+
+	// 自动填入系统库存数量
+	for i := range req.Items {
+		req.Items[i].HotelID = hotelID
+		var inv model.Inventory
+		if err := h.db.Where("hotel_id = ? AND warehouse_id = ? AND product_id = ?",
+			hotelID, req.WarehouseID, req.Items[i].ProductID).First(&inv).Error; err == nil {
+			req.Items[i].SystemQty = inv.Quantity
+		}
+	}
+
+	if err := h.db.Create(&req).Error; err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+	c.JSON(http.StatusCreated, gin.H{"data": req})
+}
+
+// GetCheck GET /api/v1/inventory/checks/:id
+func (h *InventoryHandler) GetCheck(c *gin.Context) {
+	hotelID := middleware.GetHotelID(c)
+	var check model.InventoryCheck
+	if err := h.db.Preload("Items.Product").
+		Where("id = ? AND hotel_id = ?", c.Param("id"), hotelID).
+		First(&check).Error; err != nil {
+		c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"data": check})
+}