Add group-class scheduling, instructor assignment, and details/invite management

Group classes now carry a specific class time (alongside date and duration)
and an assigned instructor:

- Schema: add `class_time` (TIME) to `us_offerings`; `Offering` gains
  `normalizeTime`/`sessionWindows`. (Rides the pending 1.0.0->1.1.0 dbDelta
  upgrade, so no version bump.)
- Offering form: class-time field, plus a studio-admin instructor picker
  (plain instructors always own their own classes).
- `ClassSlotReconciler`: assigning an instructor clears their open booking
  slots overlapping each session and flags already-booked lessons that clash
  (a booked lesson is never deleted). Uses new
  `AvailabilityRepository::findOverlapping`.
- Front end: `GET /offerings` exposes `instructor_name`; the enrolment page
  shows who teaches each class and when it meets.

Back-office group-class views redesigned:

- Instructor **My Group Classes** and studio-admin **Group Classes** are now
  per-class summaries with enrolment counts, not flat student lists.
- Each links through (`?class_id=<id>`) to a per-class **details page**
  (schedule panel, roster with payment status, and — for invite-only classes
  — the add/make-available/invite-by-email controls). Invite-only membership
  is managed entirely from this page.
- Invite actions are allowed for the class's owning instructor or any
  `view_all_lessons` studio admin, so an owner-operator (studio admin who also
  teaches) can reach every class's roster and invites from the Group Classes
  page.

Tests: composer test (508), composer lint, composer cs all pass.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/AdminMenu.php

@@ -20,6 +20,7 @@ use Unsupervised\Schedular\Booking\LessonController;
 use Unsupervised\Schedular\GroupClass\EnrollmentRepository;
 use Unsupervised\Schedular\GroupClass\GroupAccessRepository;
 use Unsupervised\Schedular\GroupClass\GroupClassController;
+use Unsupervised\Schedular\Offering\ClassSlotReconciler;
 use Unsupervised\Schedular\Offering\OfferingController;
 use Unsupervised\Schedular\Offering\OfferingRepository;
 use Unsupervised\Schedular\Payment\BillingMethodResolver;
@@ -57,7 +58,7 @@ class AdminMenu {
 	public function __construct( AvailabilityRepository $availability, BookingRepository $bookings, OfferingRepository $offerings, QuestionRepository $questions, AnswerRepository $answers, PolicyRepository $policies, PolicyVersionRepository $policyVersions, PolicyService $policyService, AcceptanceRepository $acceptances, InviteRepository $invites, EnrollmentRepository $enrollments, GroupAccessRepository $groupAccess, StudioSettings $settings, PaymentRepository $payments, PaymentService $paymentService, BillingMethodResolver $resolver, RegistrationMailer $registrationMailer ) {
 		$this->availabilityController         = new AvailabilityController( $availability, $offerings );
 		$this->lessonController               = new LessonController( $bookings, $payments, $availability );
-		$this->offeringController             = new OfferingController( $offerings );
+		$this->offeringController             = new OfferingController( $offerings, new ClassSlotReconciler( $availability ) );
 		$this->questionController             = new QuestionController( $questions, $offerings );
 		$this->policyController               = new PolicyController( $policies, $policyVersions, $policyService );
 		$this->registrationController         = new RegistrationController( $invites );