feat: add email_verified_at field to auth controller mock responses and user management service

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.

Backend/src/services/usermanagement.service.ts

@@ -183,6 +183,7 @@ export class UserManagementService {
             id: user.id,
             username: user.username,
             email: user.email,
+            email_verified_at: user.email_verified_at,
             created_at: user.created_at,
             updated_at: user.updated_at,
             role: {