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/group-classes.md

@@ -31,6 +31,37 @@ Assigning an instructor to a scheduled class removes that instructor's open
 booking slots at the class time and flags any already-booked lesson that clashes;
 see **Instructor assignment** in `offerings.md`.
 
+### Sessions in the "upcoming" views
+`GroupClass\SessionSchedule` turns an enrolment into the dated sessions behind it,
+so a class appears alongside one-to-one lessons wherever upcoming lessons are
+listed. A class is a term, not rows in `us_availability`, so an enrolment carries
+no date of its own — the concrete windows come from `Offering::sessionWindows()`,
+the same derivation the billing scan and the class-slot reconciler use, which is
+what keeps a student's list, an instructor's list and the invoice agreeing on when
+the class meets.
+
+- `upcomingForStudent()` — every not-yet-started session of each enrolment that is
+  not `cancelled`. `completed` is a *billing* state and says nothing about the
+  calendar, so those sessions stay listed.
+- `upcomingForInstructor()` — every session of each active group class they own,
+  one row per session however many students are enrolled; enrolments are not
+  consulted, because a class still has to be taught if nobody has signed up yet.
+
+A class whose schedule is not fully specified (no time, or no duration) yields no
+windows and so contributes no rows — better absent from a dated list than shown at
+a time nobody chose.
+
+Consumers mark these rows `kind = 'group_class'` (`SessionSchedule::KIND`) and
+withhold the per-lesson actions from them: a session is one date in a term, not a
+booked slot, so there is nothing to cancel session by session and no slot to
+release. Withdrawing from the class is the separate, whole-enrolment decision.
+
+Where they show up: the `[us_scheduler]` upcoming panel via `GET /bookings`
+(students and instructors both), and the **Upcoming lessons** table on the admin
+student detail page. Only *upcoming* sessions are added there — the
+**Group-class enrolments** table below already records the whole history, and a
+term's worth of past dates would bury the lessons under "Past lessons".
+
 ## Enrolment Flow
 The class list is loaded together with the student's own enrolments
 (`GET /enrollments`); a class the student already has an `active` enrolment in
@@ -175,6 +206,7 @@ class becomes enrollable for them — they choose whether to enrol.
 - Repository: `Unsupervised\Schedular\GroupClass\EnrollmentRepository` (`countActiveForOffering`/`hasActiveEnrollment` enforce capacity and prevent duplicates)
 - Access grants: `Unsupervised\Schedular\GroupClass\GroupAccess` + `GroupAccessRepository` (`hasGrant`, `findGrantedOfferingIds`, `markEnrolled`, `linkStudentByEmail`)
 - Model: `Unsupervised\Schedular\GroupClass\Enrollment`
+- Sessions: `Unsupervised\Schedular\GroupClass\SessionSchedule` (`upcomingForStudent`, `upcomingForInstructor`) — consumed by `Booking\BookingEndpoint::myLessons()` and `Auth\StudentController`
 - Admin controller: `Unsupervised\Schedular\GroupClass\GroupClassController` — `renderPage` (studio admin per-class summary, `view_all_lessons`) and `renderInstructorPage` (instructor summary + `?class_id` roster detail, `view_own_lessons`)
 - REST endpoint: `Unsupervised\Schedular\GroupClass\EnrollmentEndpoint`
 - Frontend: `Unsupervised\Schedular\GroupClass\GroupClassPage` (`[us_group_classes]` shortcode; `offering="…"` restricts it to a single class for embedding on a dedicated page — the block equivalent is the `offeringId` attribute). In single-class mode `assets/js/group-classes.js` leaves the class description out of the card, since the page it is embedded on already describes the class; the schedule, instructor, schedule note, price and enrolment controls are still shown.
@@ -193,6 +225,7 @@ class becomes enrollable for them — they choose whether to enrol.
 - `tests/Unit/GroupClass/GroupAccessTest.php`
 - `tests/Unit/GroupClass/GroupAccessRepositoryTest.php`
 - `tests/Unit/GroupClass/GroupClassPageTest.php`
+- `tests/Unit/GroupClass/SessionScheduleTest.php`
 - `tests/Unit/Offering/OfferingEndpointTest.php` (catalog merges granted invite-only classes)
 
 ## Enrolling A Child