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/init.go

@@ -141,6 +141,15 @@ func autoMigrate(db *gorm.DB) error {
 
 		// 课表
 		&ScheduleCourse{},
+
+		// 用户活跃相关
+		&UserActiveLog{},
+		&UserActivityStat{},
+
+		// 角色和权限相关
+		&Role{},
+		&UserRole{},
+		&CasbinRule{},
 	)
 	if err != nil {
 		return err