Fix people.name NOT NULL violation — fallback to name_ar when English name is empty

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Livewire/Participants/ParticipantForm.php

@@ -197,7 +197,7 @@ public function save(ParticipantService $service): void
                 // Update person data
                 $this->participant->person->update([
                     'name_ar' => $this->name_ar,
-                    'name' => $this->name ?: null,
+                    'name' => $this->name ?: $this->name_ar,
                     'gender' => $this->gender,
                     'phone' => $this->phone ?: null,
                     'email' => $this->email ?: null,
@@ -274,7 +274,7 @@ public function save(ParticipantService $service): void
                 } else {
                     $data['person'] = [
                         'name_ar' => $this->name_ar,
-                        'name' => $this->name,
+                        'name' => $this->name ?: $this->name_ar,
                         'national_id' => $this->national_id ?: null,
                         'date_of_birth' => $this->date_of_birth ?: null,
                         'gender' => $this->gender,