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/license.go

@@ -0,0 +1,71 @@
+package handler
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+	"github.com/wangjia/jiu/backend/internal/middleware"
+	"github.com/wangjia/jiu/backend/internal/service"
+)
+
+type LicenseHandler struct {
+	svc *service.LicenseService
+}
+
+func NewLicenseHandler(svc *service.LicenseService) *LicenseHandler {
+	return &LicenseHandler{svc: svc}
+}
+
+// Activate POST /api/v1/license/activate
+func (h *LicenseHandler) Activate(c *gin.Context) {
+	var req struct {
+		LicenseKey string `json:"license_key" binding:"required"`
+		DeviceID   string `json:"device_id" binding:"required"`
+	}
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	lic, err := h.svc.Activate(req.LicenseKey, req.DeviceID)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"data": lic})
+}
+
+// Verify GET /api/v1/license/verify
+func (h *LicenseHandler) Verify(c *gin.Context) {
+	hotelID := middleware.GetHotelID(c)
+	deviceID := c.Query("device_id")
+	if deviceID == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "device_id required"})
+		return
+	}
+
+	lic, err := h.svc.Verify(hotelID, deviceID)
+	if err != nil {
+		c.JSON(http.StatusForbidden, gin.H{"error": err.Error()})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"data": lic})
+}
+
+// Deactivate POST /api/v1/license/deactivate
+func (h *LicenseHandler) Deactivate(c *gin.Context) {
+	hotelID := middleware.GetHotelID(c)
+	var req struct {
+		DeviceID string `json:"device_id" binding:"required"`
+	}
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	if err := h.svc.Deactivate(hotelID, req.DeviceID); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"message": "deactivated"})
+}