public user IDs, plans priced by tutor cost, age-based tutor tone, self-service account deletion

- profile publicId ("User482917", accounts/public_id.py); admin shows and searches it
- plans API reports aiDailyQuota per plan and freeAiDailyQuota; migration 0007 sets the
  temporary prices (monthly 99,000 / yearly 990,000 toman, 5 tutor questions a day) unless
  an admin already edited the yearly plan
- tutor tone follows the learner's age (18+ gets an adult tone at any grade); notation
  still follows the grade's book; answer cache keyed by tone (prompt tutor-v12-age-tone)
- POST /api/user/delete: phone users confirm with a fresh SMS code (same checks as login,
  now shared in verify_phone_otp), guests type "حذف"; payment records are kept, demo
  accounts refused
- delete_users --skip-paid

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

accounts/tests_delete_users.py

@@ -57,3 +57,9 @@ class DeleteUsersTests(TestCase):
         self.assertFalse(User.objects.filter(pk=self.doomed.pk).exists())
         self.assertTrue(User.objects.filter(pk=self.kept.pk).exists())
         self.assertTrue(User.objects.filter(pk=guest.pk).exists())
+
+    def test_skip_paid_keeps_the_payer_and_deletes_the_rest(self):
+        Order.objects.create(user_id=self.doomed.id, amount=1000, status='paid', idempotency_key='k2')
+        self.run_command('--ids', str(self.doomed.pk), str(self.kept.pk), '--yes', '--skip-paid')
+        self.assertTrue(User.objects.filter(pk=self.doomed.pk).exists())
+        self.assertFalse(User.objects.filter(pk=self.kept.pk).exists())