Add weekly and monthly scheduled billing for offerings

Offerings can now bill weekly (a pending payment 24h before each lesson)
or monthly (one payment on the 1st for that month's lessons), alongside
one-time and full-term. Applies to both private lessons and group classes.

- Offering: new `weekly`/`monthly` billing modes + `isScheduledBilling()`
- Booking/enrolment defer payment for scheduled modes; a single lesson
  booked after its due date has passed (e.g. an add-on in an already-billed
  month) is charged at booking instead
- ScheduledBillingRunner: daily WP-Cron scan generates due payments across
  four cases (private/group × weekly/monthly), deduped via lesson.payment_id
  and payments.period_key
- PaymentDueMailer: one consolidated itemised email per student per scan
- Notice batch: payments emailed together share a reference; the admin
  Payments queue groups them with a lump-sum total for e-transfer reconciliation
- Cancellation never voids a scheduled payment (Payment::isScheduled())
- Schema: us_payments gains due_date, period_key, notice_batch; USC_VERSION 1.2.0

composer test, composer lint, composer cs all pass.

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

src/Payment/PaymentService.php

@@ -29,8 +29,12 @@ class PaymentService {
 	 * (card via Stripe — coming soon; e-transfer confirmed manually). The
 	 * e-transfer destination is frozen now from the offering override or the studio
 	 * default. Returns null when the registration has no price to charge.
+	 *
+	 * A `$dueDate`/`$periodKey` mark a payment generated later by the daily billing
+	 * scan (weekly / monthly) rather than taken at registration; both stay null for
+	 * the pay-now flow.
 	 */
-	public function createForRegistration( string $type, int $registrationId, int $studentId, int $instructorId, float $amount, string $currency, ?string $offeringEtransferEmail = null ): ?Payment {
+	public function createForRegistration( string $type, int $registrationId, int $studentId, int $instructorId, float $amount, string $currency, ?string $offeringEtransferEmail = null, ?string $dueDate = null, ?string $periodKey = null ): ?Payment {
 		if ( $amount <= 0.0 ) {
 			return null;
 		}
@@ -58,6 +62,8 @@ class PaymentService {
 				status:           $status,
 				taxRate:          $taxRate,
 				taxAmount:        $taxAmount,
+				dueDate:          $dueDate,
+				periodKey:        $periodKey,
 				etransferEmail:   $etransferEmail,
 			)
 		);
@@ -71,6 +77,26 @@ class PaymentService {
 		return $this->payments->findById( $id );
 	}
 
+	/**
+	 * Whether a scheduled payment already exists for a registration and billing
+	 * period — the daily billing scan's dedup check for group enrolments (whose one
+	 * row maps to many periodic charges). Delegates to the ledger.
+	 */
+	public function scheduledPaymentExists( string $type, int $registrationId, string $periodKey ): bool {
+		return $this->payments->existsForPeriod( $type, $registrationId, $periodKey );
+	}
+
+	/**
+	 * Tag the payments the daily scan emailed a student together with a shared
+	 * notice-batch reference, so a lump-sum e-transfer can be reconciled to the
+	 * pending payments it covers. Delegates to the ledger.
+	 *
+	 * @param list<int> $ids
+	 */
+	public function assignNoticeBatch( array $ids, string $batch ): void {
+		$this->payments->assignNoticeBatch( $ids, $batch );
+	}
+
 	/**
 	 * Studio-admin confirmation that a pending payment (e-transfer) was received.
 	 * Marks it paid, confirms the registration, and emails the receipt.
@@ -92,7 +118,10 @@ class PaymentService {
 	/**
 	 * Void the still-pending payment of a cancelled registration so it drops
 	 * out of the confirmation queue. Paid payments are left alone — refunds
-	 * are a manual, admin-side decision.
+	 * are a manual, admin-side decision. Scheduled payments (weekly / monthly)
+	 * are also left alone: a monthly charge can cover several lessons and may
+	 * already be collected, so cancelling one lesson must never void it or
+	 * trigger a rebill.
 	 */
 	public function voidPending( ?int $paymentId ): void {
 		if ( null === $paymentId ) {
@@ -100,7 +129,7 @@ class PaymentService {
 		}
 
 		$payment = $this->payments->findById( $paymentId );
-		if ( null !== $payment && Payment::STATUS_PENDING === $payment->status ) {
+		if ( null !== $payment && ! $payment->isScheduled() && Payment::STATUS_PENDING === $payment->status ) {
 			$this->payments->updateStatus( $paymentId, Payment::STATUS_FAILED );
 		}
 	}