Skip payment step for unpriced bookings, confirm them immediately, show students their lessons

Booking a slot with no priced offering created the lesson but no payment,
yet the front end still called POST /payments/intent, which 400ed with
"Could not start payment for this registration" — the student saw an error
while the backend held a claimed slot and a lesson stuck at pending.

- POST /bookings and POST /enrollments now return a `payment` summary
  ({id, method, status}) or null when nothing is owed; the JS only runs
  the payment step when a payment exists.
- Bookings with nothing owed are confirmed at creation — there is no
  payment step that would ever confirm them later.
- The booking page now shows the student's upcoming lessons (GET /bookings,
  now scoped to upcoming non-cancelled lessons with slot start/end times)
  with a pending-payment/confirmed status badge.

Fixes #53

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

src/Booking/BookingEndpoint.php

@@ -103,9 +103,24 @@ class BookingEndpoint {
 		$userId  = get_current_user_id();
 		$lessons = current_user_can( RoleManager::CAP_MANAGE_AVAILABILITY )
 			? $this->bookings->findUpcomingForInstructor( $userId )
-			: $this->bookings->findByStudent( $userId );
+			: $this->bookings->findUpcomingForStudent( $userId );
 
-		return new \WP_REST_Response( array_map( fn( Lesson $l ) => $l->toArray(), $lessons ), 200 );
+		return new \WP_REST_Response( array_map( fn( Lesson $l ): array => $this->lessonWithTimes( $l ), $lessons ), 200 );
+	}
+
+	/**
+	 * A lesson's array form plus its slot's start/end times, so front-end lists
+	 * can show when the session happens without a second request.
+	 *
+	 * @return array<string, mixed>
+	 */
+	private function lessonWithTimes( Lesson $lesson ): array {
+		$slot = $this->availability->findById( $lesson->slotId );
+
+		return $lesson->toArray() + [
+			'start_dt' => $slot?->startDt,
+			'end_dt'   => $slot?->endDt,
+		];
 	}
 
 	public function book( \WP_REST_Request $request ): \WP_REST_Response|\WP_Error {
@@ -197,14 +212,30 @@ class BookingEndpoint {
 
 		$this->gate->record( PolicyAcceptance::REG_LESSON, $anchorId, $studentId, $offeringId, $answers, $acceptedVersionIds, $this->clientIp() );
 
+		$payment = null;
+		$status  = Lesson::STATUS_PENDING;
+
 		if ( null !== $offering && $offering->price > 0.0 ) {
-			$this->payments->createForRegistration( Payment::REG_LESSON, $anchorId, $studentId, $slot->instructorId, $offering->price, $offering->currency, $offering->etransferEmail );
+			$payment = $this->payments->createForRegistration( Payment::REG_LESSON, $anchorId, $studentId, $slot->instructorId, $offering->price, $offering->currency, $offering->etransferEmail );
+
+			if ( null !== $payment && $payment->isPaid() ) {
+				$status = Lesson::STATUS_CONFIRMED;
+			}
+		} else {
+			// Nothing owed: there is no payment step that would confirm these
+			// lessons later, so they are confirmed at booking time.
+			foreach ( $ids as $lessonId ) {
+				$this->bookings->updateStatus( $lessonId, Lesson::STATUS_CONFIRMED );
+			}
+			$status = Lesson::STATUS_CONFIRMED;
 		}
 
+		// `payment: null` tells the front end to skip the payment step entirely.
 		return new \WP_REST_Response(
 			[
-				'ids'    => $ids,
-				'status' => Lesson::STATUS_PENDING,
+				'ids'     => $ids,
+				'status'  => $status,
+				'payment' => $payment?->toSummaryArray(),
 			],
 			201
 		);