feat(auth): add Casbin RBAC and user activity tracking

Integrate Casbin for role-based access control with admin routes for role management. Add user activity logging service to track login and refresh events. Refactor audit service to use AI-based content moderation.

internal/model/user_active_log.go

@@ -0,0 +1,49 @@
+package model
+
+import (
+	"time"
+)
+
+// 登录类型常量
+const (
+	LoginTypeLogin   = "login"   // 登录
+	LoginTypeRefresh = "refresh" // 刷新Token
+)
+
+// UserActiveLog 用户活跃日志
+type UserActiveLog struct {
+	ID         uint      `gorm:"primaryKey;autoIncrement" json:"id"`
+	UserID     string    `gorm:"type:varchar(36);not null;index:idx_user_date,priority:1;index" json:"user_id"` // 用户ID (UUID)
+	ActiveDate time.Time `gorm:"type:date;not null;index:idx_user_date,priority:2;index" json:"active_date"`    // 活跃日期
+	LoginType  string    `gorm:"type:varchar(20);not null" json:"login_type"`                                   // 登录类型: login/refresh
+	LoginIP    string    `gorm:"type:varchar(45)" json:"login_ip"`                                              // 登录IP
+	UserAgent  string    `gorm:"type:varchar(500)" json:"user_agent"`                                           // 用户代理
+	CreatedAt  time.Time `gorm:"autoCreateTime" json:"created_at"`
+
+	// 关联
+	User User `gorm:"foreignKey:UserID" json:"user,omitempty"`
+}
+
+// TableName 指定表名
+func (UserActiveLog) TableName() string {
+	return "user_active_logs"
+}
+
+// UserActivityStat 用户活跃统计快照
+type UserActivityStat struct {
+	ID          uint      `gorm:"primaryKey;autoIncrement" json:"id"`
+	StatType    string    `gorm:"type:varchar(10);not null;uniqueIndex:idx_type_date" json:"stat_type"` // dau/wau/mau
+	StatDate    time.Time `gorm:"type:date;not null;uniqueIndex:idx_type_date" json:"stat_date"`        // 统计日期
+	ActiveCount int64     `gorm:"not null" json:"active_count"`                                         // 活跃用户数
+	NewCount    int64     `gorm:"default:0" json:"new_count"`                                           // 新增用户数
+	Retention1  float64   `gorm:"type:decimal(5,2)" json:"retention_1"`                                 // 次日留存率
+	Retention7  float64   `gorm:"type:decimal(5,2)" json:"retention_7"`                                 // 7日留存率
+	Retention30 float64   `gorm:"type:decimal(5,2)" json:"retention_30"`                                // 30日留存率
+	CreatedAt   time.Time `gorm:"autoCreateTime" json:"created_at"`
+	UpdatedAt   time.Time `gorm:"autoUpdateTime" json:"updated_at"`
+}
+
+// TableName 指定表名
+func (UserActivityStat) TableName() string {
+	return "user_activity_stats"
+}