Version:0.0.1.dev.260202

feat: build core architecture & implement user auth modules 🚀
feat: 搭建核心架构并实现用户认证模块 🚀

Framework Migration: Switched from Hertz to Gin, providing a more idiomatic and lightweight web foundation. ⚡
框架迁移：从 Hertz 切换至 Gin，构建了更符合 Go 惯例且轻量级的 Web 基础。⚡

Architectural Overhaul: Refactored the 3-layer architecture from global-variable-based calls to Explicit Dependency Injection (DI) via New... factory functions. This significantly improves testability and decoupling. 🏗️
架构重构：将三层架构从基于“全局变量”的调用重构为通过 New... 工厂函数实现的显式依赖注入 (DI)。这大幅提升了代码的可测试性与解耦程度。🏗️

User Auth: Completed and tested Register, Login, and Token Refresh APIs with robust error handling and Bcrypt password hashing. 🔐
用户认证：完成了注册、登录与 Token 刷新接口并通过测试，包含健壮的错误处理与 Bcrypt 密码哈希加密。🔐

Config Management: Integrated Viper for centralized, environment-aware configuration management. ⚙️
配置管理：集成了 Viper，实现了中心化且具备环境感知能力的配置管理。⚙️

DevOps & Docs:
Added docker-compose.yml for seamless MySQL 8.0 & environment setup. 🐳
Updated README.md with corrections for mistakes in image quoting and formats. 📝
运维与文档：
新增 docker-compose.yml，实现 MySQL 8.0 环境的一键启动。🐳
更新 README.md，修改了一些图片引用和格式上小错误。📝

backend/dao/user.go

@@ -0,0 +1,74 @@
+package dao
+
+import (
+	"errors"
+	"time"
+
+	"github.com/smartflow/backend/model"
+	"gorm.io/gorm"
+)
+
+// UserDAO 用户数据访问对象
+// 负责用户相关的数据库操作
+type UserDAO struct {
+	// 这是一个口袋，用来装数据库连接实例
+	db *gorm.DB
+}
+
+// NewUserDAO 创建UserDAO实例
+// NewUserDAO 接收一个 *gorm.DB，并把它塞进结构体的口袋里
+func NewUserDAO(db *gorm.DB) *UserDAO {
+	return &UserDAO{
+		db: db,
+	}
+}
+
+// Create 创建新用户
+// 插入新用户信息到数据库
+func (dao *UserDAO) Create(username, phoneNumber, password string) (*model.User, error) {
+	// 创建User实例
+	user := &model.User{
+		Username:    username,
+		PhoneNumber: phoneNumber,
+		Password:    password,   // 注意：实际项目中应该对密码进行加密处理
+		TokenLimit:  100000,     // 默认值
+		TokenUsage:  0,          // 初始使用量为0
+		LastResetAt: time.Now(), // 设置为当前时间
+	}
+
+	// 插入数据
+	if err := dao.db.Create(user).Error; err != nil {
+		return nil, err
+	}
+
+	return user, nil
+}
+
+func (dao *UserDAO) IfUsernameExists(name string) (bool, error) {
+	err := dao.db.Where("username = ?", name).First(&model.User{}).Error
+	if err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return false, nil
+		}
+		return true, err
+	}
+	return true, nil
+}
+
+func (dao *UserDAO) GetUserHashedPasswordByName(name string) (string, error) {
+	var user model.User
+	err := dao.db.Where("username = ?", name).First(&user).Error
+	if err != nil {
+		return "", err
+	}
+	return user.Password, nil
+}
+
+func (dao *UserDAO) GetUserIDByName(name string) (int, error) {
+	var user model.User
+	err := dao.db.Where("username = ?", name).First(&user).Error
+	if err != nil {
+		return -1, err
+	}
+	return int(user.ID), nil
+}