fix(patient): derive is_paid from remaining, recompute on edit, audit add-payment

- is_paid now = remaining_rials == 0 (was payment_method != pending), so adding
  a service/package after settlement correctly flips the session back to debtor.
- updateSessionServices recomputes the cached settlement (payment_method/paid_at)
  after totals change.
- addSessionPayment now records a 'create' audit entry (actor, amount, time).

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

src/Patient/Entity/PatientSession.php

@@ -244,7 +244,7 @@ class PatientSession
             'services_total_rials'               => $this->servicesTotalRials,
             'final_price_rials'                  => $this->finalPriceRials,
             'payment_method'                     => $this->paymentMethod,
-            'is_paid'                            => $this->paymentMethod !== 'pending',
+            'is_paid'                            => $this->getRemainingRials() === 0,
             'discount_type'                      => $this->discountType,
             'discount_value'                     => $this->discountValue,
             'discount_rials'                     => $this->discountRials,

src/Patient/Service/PatientService.php

@@ -369,6 +369,9 @@ class PatientService
         $session->setFinalPriceRials($priceCalc['final_price_rials'] + $session->getConsumablesTotalRials());
         $this->sessionRepo->save($session);
 
+        // پس از تغییر مبلغ، وضعیت تسویه بازمحاسبه شود (افزودن سرویس/پکیج → بدهکار).
+        $this->recomputeSettlement($session);
+
         // ثبت audit برای فیلدهای تغییرکرده
         $after = [
             'visit_price_rials'    => (string) $session->getVisitPriceRials(),
@@ -587,6 +590,8 @@ class PatientService
         }
         $this->sessionRepo->save($session);
 
+        $this->logSessionChange($session, 'payment', \App\Patient\Entity\SessionAuditLog::OP_CREATE, null, (string) $amountRials, $actor, 'ثبت پرداخت');
+
         return $payment;
     }
 }