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>

rag/services/retrieval.py

@@ -10,7 +10,9 @@ import logging
 
 from .config import build_collection_name, resolve_grade_title, retrieval_top_k
 from .embedding import embed_text
-from .known_collections import filter_key_for_subject, is_math_subject, resolve_math_chapter
+from .known_collections import (
+    KNOWN_COLLECTIONS, filter_key_for_subject, is_math_subject, resolve_math_chapter,
+)
 from .qdrant_store import search
 
 logger = logging.getLogger(__name__)
@@ -29,6 +31,12 @@ def resolve_target(subject: str, grade_title: str, grade_id, lesson_number):
         return None, None, None
 
     collection = build_collection_name(subject, grade_title)
+    if collection not in KNOWN_COLLECTIONS:
+        # subject و grade می‌توانند از بدنه‌ی درخواست بیایند؛ بی‌این چک هر کاربری از هر collectionِ
+        # Qdrantِ مشترک (از جمله مالِ تیمِ دیگر) متن می‌خواند و در usedChunks پس می‌گرفت.
+        # نتیجه همان رفتارِ collectionِ ناموجود است: جوابِ بی‌context.
+        logger.warning('rag.retrieve: collection %r در KNOWN_COLLECTIONS نیست، جستجو نشد', collection)
+        return None, None, None
     filter_key = filter_key_for_subject(subject)
     if is_math_subject(subject):
         filter_value = resolve_math_chapter(subject, grade_title, lesson_number)