Security review fixes: admin permissions, guest sessions, payment edge cases, assistant leaks

- Admin: refund/cancel/mark-resolved/Bazaar-link actions need change permission; question and
  curriculum import need add/delete; content browser needs view_question; guest device ids are
  shown to superusers only.
- Accounts: registering a guest's phone revokes the guest's earlier sessions; self-deletion keeps
  Redemption, UserOffer and the phone's OTP rows; the public demo guest cannot be deleted
  (DEMO_GUEST_DEVICE_IDS); display-name contact filter covers any separator and social handles.
- Payment: callback without Authority is 400; a second Bazaar purchase on a paid order is 409;
  orders snapshot credits/hearts/days at creation (payment.0011).
- Assistant: a broken diagram no longer makes a streamed answer free; a late off-topic marker
  refuses the answer (not stored, not cached); a disconnect saves the partial answer; only
  KNOWN_COLLECTIONS are searched.
- Infra: secret-key file is created atomically (workers no longer split keys); no default
  INTERNAL_SERVICE_KEY; Kavenegar key and Bazaar token kept out of error logs; Swagger/ReDoc
  pinned; schema throttled; docker compose bound to 127.0.0.1; non-ASCII digit ids are 400;
  ticket text capped at 5000.
- docs/security-before-production.md: remaining open items 24-31 and the guard tests.

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

accounts/serializers.py

@@ -5,16 +5,23 @@ from rest_framework import serializers
 from .phone import normalize_phone
 
 # لینک، آیدیِ شبکه‌ی اجتماعی، و هر رشته‌ی ۵ رقمی یا بیشتر (شماره‌ی تلفن با
-# فاصله/خط‌تیره هم) — ارقامِ فارسی و عربی هم.
+# فاصله/خط‌تیره هم) — ارقامِ فارسی و عربی هم. این نام در رتبه‌بندی به بچه‌های دیگر نشان داده می‌شود.
 _CONTACT = re.compile(
     r'(https?://\S+|www\.\S+|\S+\.(?:com|ir|org|net|me)\S*|@\w+'
-    r'|(?:[0-9۰-۹٠-٩][\s\-.]?){5,})',
+    r'|(?:[0-9۰-۹٠-٩][\s\-._/\\|,،]*){5,})',
+    re.IGNORECASE,
+)
+# «ig: name»، «insta name»، «آیدی name» و مانندش: کلیدواژه و هر چه بعدش آمده حذف می‌شود.
+_HANDLE = re.compile(
+    r'(?:\b(?:ig|insta(?:gram)?|tele(?:gram)?|tg|id|whats ?app|rubika|eitaa|bale)\b'
+    r'|اینستا\S*|(?:تلگرام|تل|آیدی|ایدی|واتساپ|روبیکا|ایتا)(?!\w)|بله\s*:)\s*[:：]?.*',
     re.IGNORECASE,
 )
 
 
 def clean_display_name(value: str) -> str:
-    return ' '.join(_CONTACT.sub(' ', value or '').split())[:30]
+    value = _HANDLE.sub(' ', value or '')
+    return ' '.join(_CONTACT.sub(' ', value).split())[:30]
 
 
 class IranMobileField(serializers.CharField):