feat(appointment): auto-expire unpaid bookings via Symfony Scheduler

Run the 15-min payment-expiry every minute through Symfony Scheduler so
unpaid pending bookings flip to expired without a system crontab. Install
symfony/scheduler; extract the expiry logic into AppointmentExpiryService
(reused by the existing command); add ExpireAppointmentsMessage + handler
and an #[AsSchedule] provider (RecurringMessage::every 1 minute); wire a
scheduler_default transport in messenger.yaml. Slots already free
just-in-time via isSlotTaken, so this only syncs the DB status.

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

config/packages/messenger.yaml

@@ -11,9 +11,12 @@ framework:
                     multiplier: 2
             failed: 'doctrine://default?queue_name=failed'
             sync: 'sync://'
+            scheduler_default:
+                dsn: 'schedule://appointment_expiry'
 
         routing:
             'App\Shared\Message\SendSmsMessage': async
+            'App\Appointment\Message\ExpireAppointmentsMessage': scheduler_default
 
 when@test:
     framework: