refactor(scheduler): use the recipe's default stateful schedule

Consolidate onto the symfony/scheduler recipe's App\Schedule (stateful +
processOnlyLastMissedRun, so missed runs after downtime still execute)
instead of a separate provider. Add the every-1-minute
ExpireAppointmentsMessage there, point scheduler_default at
schedule://default, and drop the redundant ExpireAppointmentsSchedule.
debug:scheduler shows the trigger registered.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/Appointment/Schedule/ExpireAppointmentsSchedule.php

@@ -1,20 +0,0 @@
-<?php
-
-namespace App\Appointment\Schedule;
-
-use App\Appointment\Message\ExpireAppointmentsMessage;
-use Symfony\Component\Scheduler\Attribute\AsSchedule;
-use Symfony\Component\Scheduler\RecurringMessage;
-use Symfony\Component\Scheduler\Schedule;
-use Symfony\Component\Scheduler\ScheduleProviderInterface;
-
-#[AsSchedule('appointment_expiry')]
-final class ExpireAppointmentsSchedule implements ScheduleProviderInterface
-{
-    public function getSchedule(): Schedule
-    {
-        return (new Schedule())->add(
-            RecurringMessage::every('1 minute', new ExpireAppointmentsMessage())
-        );
-    }
-}