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>

docs/operations.md

@@ -110,6 +110,12 @@ curl https://api.math.tadrisino2.ir/api/health
 | `FRONTEND_URL` · `ZARINPAL_REDIRECT_URL` | بعد از پرداخت کاربر به `https://math.tadrisino2.ir/?orderId=…&status=paid\|failed` برمی‌گردد. `ZARINPAL_REDIRECT_URL=-` یعنی همان پاسخِ JSONِ قدیمی |
 | `OPENAI_API_KEY` · `QDRANT_API_KEY` | `POST /api/ai/ask` همان پاسخِ stub را می‌دهد |
 | `TEST_LOGIN_PHONES` | هیچ حسابِ تستی باز نیست (بخشِ بعد) |
+| `HEARTS_ENFORCED` | خاموش: با صفر قلب هم می‌شود جواب داد. `1` وقتی فرانت برای ۴۰۳ِ `no_hearts` صفحه‌ی «قلب‌ها تمام شد» دارد |
+| `INTERNAL_SERVICE_KEY` | endpointهای داخلیِ ingestِ RAG و ساختِ سفارشِ سرور-به-سرور بسته‌اند |
+
+**پرداخت‌های تأییدنشده:** اپ هر بار که وضعیتِ اشتراک را می‌خواند، سفارش‌های
+pendingِ همان کاربر را دوباره با زرین‌پال می‌سنجد. برای دیدنِ همه یک‌جا:
+`python manage.py payment_reconcile --days 3`.
 
 > **`DJANGO_SECRET_KEY` توکن‌های ورود را امضا می‌کند.** بهترین حالت این است که
 > اصلاً ست نشود تا خودِ تنظیمات یکی بسازد — آن‌وقت کلیدی وجود ندارد که لو