feat: support multiple services per appointment (checkbox selection)

Appointments could only reference a single service (ManyToOne). Add an
appointment_service_items join table (ManyToMany) so an appointment can
carry several services; the first stays the primary service_item for
backward compatibility, and toArray now also returns service_items[].

Both create endpoints (my/appointment, admin/appointment) accept
service_item_uuids[] and attach all of them. A new duration_from_services
flag gates the slot_end recompute: service-booking mode sends it true
(slot_end = start + Σ durations); slot mode omits it so the manual end
time is preserved. The admin endpoint previously ignored services entirely.

Frontend: in slot mode the single service dropdown becomes a checkbox list
filtered by the selected section (multi-select); service mode sends the
duration flag. Migration + backend/entity tests + docs updated.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/Appointment/Entity/Appointment.php

@@ -4,6 +4,8 @@ namespace App\Appointment\Entity;
 
 use App\Auth\Entity\User;
 use App\Doctor\Entity\Doctor;
+use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\Common\Collections\Collection;
 use Doctrine\ORM\Mapping as ORM;
 use App\Appointment\Repository\AppointmentRepository;
 use Symfony\Component\Uid\Uuid;
@@ -135,11 +137,16 @@ class Appointment
     #[ORM\JoinColumn(name: 'service_section_id', nullable: true, onDelete: 'SET NULL')]
     private ?\App\ClinicService\Entity\ServiceSection $serviceSection = null;
 
-    /** سرویس — concrete service item to perform. */
+    /** سرویس — سرویس اصلی/اولِ نوبت (برای سازگاری با مصرف‌کننده‌های موجود). */
     #[ORM\ManyToOne(targetEntity: \App\ClinicService\Entity\ServiceItem::class)]
     #[ORM\JoinColumn(name: 'service_item_id', nullable: true, onDelete: 'SET NULL')]
     private ?\App\ClinicService\Entity\ServiceItem $serviceItem = null;
 
+    /** سرویس‌های نوبت — امکان انتخاب چند سرویس. serviceItem بالا همان سرویسِ اول است. */
+    #[ORM\ManyToMany(targetEntity: \App\ClinicService\Entity\ServiceItem::class)]
+    #[ORM\JoinTable(name: 'appointment_service_items')]
+    private Collection $serviceItems;
+
     /** پرسنل — staff member assigned to the appointment. */
     #[ORM\ManyToOne(targetEntity: \App\Staff\Entity\ClinicStaff::class)]
     #[ORM\JoinColumn(name: 'staff_id', nullable: true, onDelete: 'SET NULL')]
@@ -174,6 +181,7 @@ class Appointment
         $this->slotEnd   = $slotEnd;
         $this->createdAt = time();
         $this->updatedAt = time();
+        $this->serviceItems = new ArrayCollection();
         $this->refreshActiveSlotKey();
     }
 
@@ -219,6 +227,21 @@ class Appointment
 
     public function getServiceSection(): ?\App\ClinicService\Entity\ServiceSection { return $this->serviceSection; }
     public function getServiceItem(): ?\App\ClinicService\Entity\ServiceItem { return $this->serviceItem; }
+
+    /** @return Collection<int,\App\ClinicService\Entity\ServiceItem> */
+    public function getServiceItems(): Collection { return $this->serviceItems; }
+
+    public function addServiceItem(\App\ClinicService\Entity\ServiceItem $item): self
+    {
+        if (!$this->serviceItems->contains($item)) {
+            $this->serviceItems->add($item);
+        }
+        // سرویسِ اصلی = اولین سرویس، تا مصرف‌کننده‌های موجود کار کنند.
+        if ($this->serviceItem === null) {
+            $this->serviceItem = $item;
+        }
+        return $this;
+    }
     public function getStaff(): ?\App\Staff\Entity\ClinicStaff { return $this->staff; }
     public function isDepositRequired(): bool { return $this->depositRequired; }
     public function getDepositAmountRials(): ?int { return $this->depositAmountRials; }
@@ -317,6 +340,10 @@ class Appointment
             'patient_reason'        => $this->patientReason,
             'service_section' => $this->serviceSection ? ['uuid' => $this->serviceSection->getUuid(), 'name' => $this->serviceSection->getName()] : null,
             'service_item'    => $this->serviceItem ? ['uuid' => $this->serviceItem->getUuid(), 'name' => $this->serviceItem->getName()] : null,
+            'service_items'   => array_map(
+                fn(\App\ClinicService\Entity\ServiceItem $i) => ['uuid' => $i->getUuid(), 'name' => $i->getName()],
+                $this->serviceItems->toArray()
+            ),
             'staff'           => $this->staff ? ['uuid' => $this->staff->getUuid(), 'full_name' => $this->staff->getFullName()] : null,
             'deposit_required'     => $this->depositRequired,
             'deposit_amount_rials' => $this->depositAmountRials,