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>

payment/bazaar.py

@@ -295,8 +295,9 @@ def verify_purchase(*, product_sku: str, purchase_token: str,
             url = f'{settings.BAZAAR_API_BASE}/api/validate/{pkg}/inapp/{sku}/purchases/{token}/'
         try:
             resp = requests.get(url, headers=_auth_headers(), timeout=10)
-        except requests.RequestException:
-            logger.exception('Bazaar verify-purchase request failed')
+        except requests.RequestException as exc:
+            # فقط نوعِ خطا: متنِ خطا آدرس را دارد و توکنِ خریدِ کاربر بخشی از آن است.
+            logger.error('Bazaar verify-purchase request failed: error=%s', type(exc).__name__)
             raise BazaarAPIError()
         try:
             return resp.status_code, resp.json()