Audit fixes 2026-10-03: seed keeps admin edits, plan cache, refresh limit, payment and tutor guards

- seed_content no longer undoes admin work: a SeedRecord ledger (content/seed_sync.py)
  stops deleted/renamed/re-worded content from being recreated and keeps admin-edited
  lesson text; new rows in the seed files still arrive (migration content.0010)
- plan list cache is invalidated on Plan save (receiver used a stale 'v1' key)
- token refresh per-IP cap 30/hour -> 600/hour (TOKEN_REFRESH_IP_RATE)
- a failed gateway result only changes a pending order (forged NOK no longer
  overwrites refunded/canceled)
- tutor gets the correct answer only after the student has answered
- support reply notification moved to a TicketMessage post_save signal
- global daily cap on paid AI questions (AI_GLOBAL_DAILY_MAX, default 3000)
- Bazaar verify uses only the order's SKU; bazaar orders require a SKU
- /api/health warns on the committed signing key; deploy.sh saves local commits;
  400 for bad ?unit= / ?period=; account delete keeps the referrer's Conversion
- earlier today: no stub answers outside DEBUG, ?grade= removed, logged fallbacks

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

.env.example

@@ -110,6 +110,10 @@ BAZAAR_REFRESH_TOKEN=
 # سقفِ خواندن روی اندپوینت‌های پرترافیک، و سقفِ /api/health.
 # READ_THROTTLE_RATE=120/min
 # HEALTH_THROTTLE_RATE=60/min
+# سقفِ تمدیدِ توکن برای هر IP (همه‌ی کاربرانِ پشتِ یک وای‌فای یا CGNAT با هم).
+# TOKEN_REFRESH_IP_RATE=600/hour
+# سقفِ روزانه‌ی کلِ سامانه برای سوال‌هایی که به مدلِ هوش مصنوعی می‌رسند (ضدِ خرجِ بی‌سقف).
+# AI_GLOBAL_DAILY_MAX=3000
 # کشِ پاسخِ دستیار (ثانیه)؛ سوالِ تکراری دوباره به مدل نمی‌رود.
 # RAG_ANSWER_CACHE_TTL=1800
 # 1 = دستیار حتی با کلیدها هم پاسخِ آزمایشی بدهد.