feat(appointment): identify admin-booked patient by national code

Admin-side booking (POST /api/v1/my/appointment and
/api/v1/admin/appointment) resolved the patient User by mobile only, so
one person booked under two mobiles produced two User rows — and two
case-files, since PatientRecord is keyed on user_id. National code is the
real unique identity (User.national_code is already unique); a person may
have several mobiles.

Booking now requires + validates patient_national_code and resolves the
patient national-code-first (then mobile) via a shared PatientResolver, so
the case-file stays unique per national code even across mobiles. Reusing a
mobile already bound to a different national code returns 422
ERR_PROFILE_MOBILE_TAKEN. The admin create form and NewAppointmentDrawer
gain a national-code field and send it; both had a dead patient-picker URL
(/api/v1/patient) fixed to the real /api/v1/patients, whose payload already
carries user_national_code for autofill.

Docs (appointment.md, admin.md) and tests updated; new
AppointmentNationalCodeTest covers success, single-file reuse, missing,
invalid, and identity-conflict cases.

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

tests/Appointment/BookingScopeTest.php

@@ -27,11 +27,12 @@ class BookingScopeTest extends ApiTestCase
         $start = time() + 86_400;
 
         return [
-            'doctor_uuid'    => $doctorUuid,
-            'slot_start'     => $start,
-            'slot_end'       => $start + 1_800,
-            'patient_mobile' => '09120000000',
-            'patient_name'   => 'بیمار تست',
+            'doctor_uuid'           => $doctorUuid,
+            'slot_start'            => $start,
+            'slot_end'              => $start + 1_800,
+            'patient_mobile'        => '09' . str_pad((string) random_int(0, 999_999_999), 9, '0', STR_PAD_LEFT),
+            'patient_name'          => 'بیمار تست',
+            'patient_national_code' => '00' . str_pad((string) random_int(0, 99_999_999), 8, '0', STR_PAD_LEFT),
         ];
     }