Convert formatUserResponse to async method to support presigned URL generation for avatar_url field. Add getAvatarPresignedUrl helper method to generate 1-hour expiry presigned URLs for user avatars. Update listUsers and getUserById to await formatUserResponse calls.
Add email_verified_at field to mock user responses in login, registerInstructor, and registerStudent endpoints. Include email_verified_at in UserManagementService user response mapping to ensure consistency across all user-related endpoints.
