feat(appointment): log cancellation events and show them in a Timeline

Introduce the first per-appointment event system. On cancel (via the status
or general update endpoints) an AppointmentEvent (type=cancelled, «نوبت لغو
شد») is recorded with the actor, cancel time, and an optional cancel_reason,
plus a warning-level app_log entry. New GET /appointment/{uuid}/events
returns the ordered event list. The admin appointment detail page renders a
Timeline section and the cancel dialog now collects an optional reason.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/Appointment/Repository/AppointmentEventRepository.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace App\Appointment\Repository;
+
+use App\Appointment\Entity\AppointmentEvent;
+use Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepository;
+use Doctrine\Persistence\ManagerRegistry;
+
+class AppointmentEventRepository extends ServiceEntityRepository
+{
+    public function __construct(ManagerRegistry $registry) { parent::__construct($registry, AppointmentEvent::class); }
+
+    public function save(AppointmentEvent $e, bool $flush = true): void
+    {
+        $this->getEntityManager()->persist($e);
+        if ($flush) {
+            $this->getEntityManager()->flush();
+        }
+    }
+
+    /** رویدادهای یک نوبت به‌ترتیب زمان (قدیمی → جدید)، به‌صورت آرایه. */
+    public function findByAppointmentUuid(string $appointmentUuid): array
+    {
+        return $this->createQueryBuilder('e')
+            ->select('e.type AS type', 'e.title AS title', 'e.actorName AS actor_name', 'e.reason AS reason', 'e.createdAt AS created_at')
+            ->join('e.appointment', 'a')
+            ->where('a.uuid = :uuid')->setParameter('uuid', $appointmentUuid)
+            ->orderBy('e.createdAt', 'ASC')
+            ->getQuery()->getArrayResult();
+    }
+}