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>

deploy/docker-compose.yml

@@ -0,0 +1,29 @@
+version: "3.9"
+
+services:
+  mysql:
+    image: mysql:8.0
+    container_name: jiu_mysql
+    restart: unless-stopped
+    environment:
+      MYSQL_ROOT_PASSWORD: password
+      MYSQL_DATABASE: jiu_db
+      MYSQL_CHARSET: utf8mb4
+    ports:
+      - "3306:3306"
+    volumes:
+      - mysql_data:/var/lib/mysql
+      - ../backend/schema/schema.sql:/docker-entrypoint-initdb.d/schema.sql:ro
+    command: --character-set-server=utf8mb4 --collation-server=utf8mb4_unicode_ci
+
+  adminer:
+    image: adminer
+    container_name: jiu_adminer
+    restart: unless-stopped
+    ports:
+      - "8888:8080"
+    depends_on:
+      - mysql
+
+volumes:
+  mysql_data: