Demo follow-ups: editable policy name, one-page signup, group classes in upcoming lessons, deletion cleanup

Five items from the latest demo pass:

- A policy's title can be edited from the Policies screen. Only the title
  moves; the slug is what the gates resolve policies by, so a rename can
  never detach a policy from acceptances already recorded against it.
- Signup is one page again. The studio's registration questions move from
  a second step behind "Next" onto the main form, in an "About you" panel
  above the students being added, and that panel also asks an adult
  student for their birth year (the same us_birth_year meta a child's
  uses). register.js disables and hides the whole panel for a pure
  guardian, since the questions describe a student.
- The password is re-scored on submit, not only as it is typed. zxcvbn's
  dictionary arrives after page load, so a password typed straight away
  was never scored at all and the first the student heard of it was the
  server rejecting the whole form.
- Group-class sessions appear alongside lessons wherever upcoming lessons
  are listed: the [us_scheduler] panel (students and instructors) and the
  admin student detail page. GroupClass\SessionSchedule derives them from
  Offering::sessionWindows(), the same derivation the billing scan uses.
  They carry kind = 'group_class' and no Cancel action - a session is one
  date in a term, not a booked slot.
- Deleting a user releases what the account was holding: each upcoming
  lesson is cancelled, its slot freed for rebooking, its pending payment
  voided, and active class enrolments cancelled. Past lessons and paid
  history are left alone.

Tests: composer test (851), composer lint, composer cs all pass.

Co-Authored-By: Claude Opus 5 <[email protected]>

docs/features/account-registration.md

@@ -106,19 +106,33 @@ thresholds reach JavaScript via `wp_localize_script()` from the same constants
 the server enforces, so the two cannot drift apart.
 
 The verdict is applied with `setCustomValidity()` on the password field rather
-than by disabling a button: the form has up to three submits plus a "Next" that
-already gates on `checkValidity()`, and an invalid field stops all of them
-without any needing to know why. zxcvbn's dictionary loads asynchronously, so
-the gate stays open until it arrives — the server is the check that always runs.
+than by disabling a button: an invalid field stops the submit without the button
+needing to know why. zxcvbn's dictionary loads asynchronously, so the gate stays
+open until it arrives — the server is the check that always runs.
 
-## Registration Questions (signup step two)
+The password is also **re-scored on submit**, not only as it is typed. Native
+validation has already run by the time the `submit` event fires, so a verdict
+reached there stops the submit by hand (`preventDefault()` + `reportValidity()`).
+Without that, a password typed in the second before the dictionary arrived was
+never scored at all, and the first the person heard of it was the server
+rejecting the whole form.
+
+## Registration Questions
 When the studio has configured **account-scope** registration questions
-(**Offerings → Questions → "Account signup"**, see `registration-questions.md`), the
-registration form becomes two steps: name/email/password/policies first, then the required
-questions. This applies to **every** signup path (invite, group link, self-approval).
-Required answers are validated before the account is created, and are stored against the new
-user (`us_question_answers`, `registration_type = 'account'`). A studio admin reviews them
-under **Registration Information** on the student's admin screen.
+(**Offerings → Questions → "Account signup"**, see `registration-questions.md`), they
+are asked on the main form in an **About you** panel — alongside the account
+holder's birth year, above the students they are adding, and only when they are a
+student themselves (`self` or `both`). This applies to **every** signup path
+(invite, group link, self-approval). Required answers are validated before the
+account is created, and are stored against the new user (`us_question_answers`,
+`registration_type = 'account'`). A studio admin reviews them under **Registration
+Information** on the student's admin screen.
+
+The form is one page with one submit. The questions used to be a second step
+behind a "Next" button; that put what the studio needs to know about an adult
+student on a screen reached only after everything else, and the two-step gate is
+what made a weak password reachable — it advanced on a `checkValidity()` that had
+not yet scored anything.
 
 ## Policy Acceptance Scope
 Policies declare **when** they must be accepted via `us_policies.acceptance_scope`:
@@ -201,10 +215,10 @@ No-op when no registration page is set.
 - `tests/Unit/Payment/StudioSettingsTest.php`
 
 ## Parent/Guardian Signup
-The registration form also offers **"I'm registering as a parent or guardian"**,
-which reveals a repeatable child block (name, birth year, and the
-account-scope questions asked **per child**). Each child becomes a login-less
-`us_student` user linked to the guardian, and the signup policies are recorded
-once per child with the guardian as the acceptor. Available on every signup path
-— personal invite, group link, and self-approval. See
-`parent-guardian-accounts.md`.
+The registration form asks **"Who are you registering?"** — just myself, on behalf
+of one or more students, or both — and the student-bearing choices reveal a
+repeatable child block (name, birth year, and the account-scope questions asked
+**per child**). Each child becomes a login-less `us_student` user linked to the
+guardian, and the signup policies are recorded once per child with the guardian as
+the acceptor. Available on every signup path — personal invite, group link, and
+self-approval. See `parent-guardian-accounts.md`.