API.5 Teachers enroll a class: invite, active on the click (API + /account/students)

An active teacher in the Student Program enrolls a list, on /account/students or POST /v1/education/students (the same service): up to 200 a call, 500 invites a day, 300 students unless staff raise it. Each student gets one email; /education-join needs a real click, then the license is active with no staff review, prices locked as at apply. Invites expire after 30 days. List, edit, resend, CSV; a student can say "This isn't for me" and is not invited again. Taking a student off the list: an unanswered invite ends; someone who joined keeps the versions covered until then and new versions stop, and they can answer a new check if they are still a student. Real mail to a student has not been sent yet (tests only log it).