tutor answers step by step in plain text, islands finish, and the audit's money and login holes are closed

Tutor (prompt tutor-v3-stepwise-plain): plain text instead of LaTeX/markdown,
with rag/services/mathtext.py converting whatever still slips through; full
step-by-step solutions with a check before the final answer; three tones by
grade; the last 6 messages of the conversation go to the model and follow-ups
are no longer served from another user's cache; book solutions the checker
disputes are kept out of the context; a questionId gives the tutor the
practice question and the student's wrong answer. /api/health reports when
the AI credit runs out. rag_model_benchmark compares chat models on verified
book problems (run on the server; credit ran out mid-run).

Map: only lessons that have questions count toward finishing an island,
lessonIds[0] / nextLessonId is always the next lesson to play, and a finished
island stays finished. The Seyar characters (sigma/delta/pi) are seeded.

Audit fixes, each reproduced before fixing:
- the plan is stored on the order, so paying a monthly order after starting
  a yearly checkout no longer grants a year
- opening checkout no longer demotes an active subscription; renewals extend
  from the current expiry; expired subscriptions are not reported active
- one discount code per order and only before the gateway; a 100% code
  completes the purchase; lost Zarinpal confirmations are re-verified
- the unused /api/payment/webhook "mark paid" endpoint is removed
- XP counts only answers recorded on the server
- 6-digit OTP, each code dies after 5 wrong guesses; POST /api/auth/logout
- a guest who signs up keeps their account and progress (test phones excluded)
- affiliate commission on the first real payment; guests excluded
- parents with several children no longer get a 500
- SQLite runs transactions IMMEDIATE, since it ignores select_for_update
- admin login is rate-limited; display names drop phone numbers and links;
  userQuestion is capped at 2000 characters
- server-side heart enforcement exists behind HEARTS_ENFORCED (off until the
  frontend handles 403 no_hearts)

Not done on purpose: rotating the server's secret key and moving to Postgres.

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

payment/management/commands/payment_reconcile.py

@@ -0,0 +1,28 @@
+"""
+سفارش‌های pendingِ زرین‌پال را دوباره verify می‌کند.
+
+همین کار برای هر کاربر خودکار هم انجام می‌شود (وقتی اپ وضعیتِ اشتراک یا
+سفارش را می‌پرسد)؛ این فرمان برای وقتی است که بخواهید همه را یک‌جا ببینید:
+
+    python manage.py payment_reconcile --days 3
+"""
+from django.core.management.base import BaseCommand
+from django.utils import timezone
+
+from payment.models import Order
+from payment.services import reconcile_pending_order
+
+
+class Command(BaseCommand):
+    help = 'verifyِ دوباره‌ی سفارش‌های pendingِ زرین‌پال'
+
+    def add_arguments(self, parser):
+        parser.add_argument('--days', type=int, default=3)
+
+    def handle(self, *args, **opts):
+        since = timezone.now() - timezone.timedelta(days=opts['days'])
+        orders = list(Order.objects.filter(
+            status='pending', provider='gateway', created_at__gte=since,
+        ).exclude(gateway_authority=''))
+        fixed = sum(1 for order in orders if reconcile_pending_order(order))
+        self.stdout.write(f'{len(orders)} سفارشِ pending بررسی شد؛ {fixed} سفارش paid شد.')