Reconcile up-front charges when a class switches to monthly billing

A student who enrols while a group class is pay-now is charged once at
enrolment, and that charge carries no period_key. When the class is
later switched to monthly, the daily scan — which dedups scheduled
charges by period_key — does not see the up-front charge and bills the
enrolment again for the current month, double-charging students who
had already paid. The differing payer between the two rows (student vs
guardian) was a side effect of guardian links created between the two
charge dates, not the cause.

Switching a group class into monthly now adopts each active enrolment's
up-front charge into the current month (stamping period_key and
due_date) so the scan treats that month as billed and charges from the
next month on. Enrolments with no up-front charge, or already billed
for the month, are left alone; weekly and non-group offerings are not
touched. Wired into both offering-update paths (admin form and REST).

Co-authored-by: anthropic/claude-opus-4-8

src/RestRegistrar.php

@@ -15,6 +15,7 @@ use Unsupervised\Schedular\GroupClass\GroupAccessRepository;
 use Unsupervised\Schedular\GroupClass\EnrollmentRepository;
 use Unsupervised\Schedular\GroupClass\SessionSchedule;
 use Unsupervised\Schedular\Guardian\GuardianService;
+use Unsupervised\Schedular\Offering\BillingModeReconciler;
 use Unsupervised\Schedular\Offering\OfferingEndpoint;
 use Unsupervised\Schedular\Offering\OfferingRepository;
 use Unsupervised\Schedular\Payment\PaymentEndpoint;
@@ -40,10 +41,10 @@ class RestRegistrar {
 	private EnrollmentEndpoint $enrollmentEndpoint;
 	private PaymentEndpoint $paymentEndpoint;
 
-	public function __construct( AvailabilityRepository $availability, BookingRepository $bookings, OfferingRepository $offerings, QuestionRepository $questions, PolicyRepository $policies, PolicyVersionRepository $policyVersions, PolicyService $policyService, RegistrationGate $gate, EnrollmentRepository $enrollments, GroupAccessRepository $groupAccess, PaymentService $paymentService, GuardianService $guardians, LessonBooker $booker ) {
+	public function __construct( AvailabilityRepository $availability, BookingRepository $bookings, OfferingRepository $offerings, QuestionRepository $questions, PolicyRepository $policies, PolicyVersionRepository $policyVersions, PolicyService $policyService, RegistrationGate $gate, EnrollmentRepository $enrollments, GroupAccessRepository $groupAccess, PaymentService $paymentService, GuardianService $guardians, LessonBooker $booker, BillingModeReconciler $billingModeReconciler ) {
 		$this->availabilityEndpoint = new AvailabilityEndpoint( $availability, new WindowValidator( $offerings ) );
 		$this->bookingEndpoint      = new BookingEndpoint( $availability, $bookings, $offerings, $gate, $paymentService, $booker, new CancellationPolicy( new StudioSettings() ), $guardians, new SessionSchedule( $enrollments, $offerings ) );
-		$this->offeringEndpoint     = new OfferingEndpoint( $offerings, $groupAccess );
+		$this->offeringEndpoint     = new OfferingEndpoint( $offerings, $groupAccess, $billingModeReconciler );
 		$this->questionEndpoint     = new QuestionEndpoint( $questions, $offerings );
 		$this->policyEndpoint       = new PolicyEndpoint( $policies, $policyVersions, $policyService );
 		$this->enrollmentEndpoint   = new EnrollmentEndpoint( $enrollments, $offerings, $gate, $paymentService, $groupAccess, $guardians );