Finishing a lesson or island needs recorded answers and an unlocked island; auto DB backup before migrate; throttles on 15 more routes

- content: POST nodes/{id}/quiz/complete and lessons/{id}/complete refuse a locked island
  (403 node_locked, same rule as /api/home) and a user who has not answered every question
  (409 answers_missing). Before, only a user with zero hearts and no answers was refused, so
  anyone else finished any island, locked or not, and finishing a locked island's lessons
  unlocked it. A node or lesson with no questions still passes when unlocked, with no XP.
  The client can no longer understate totalQuestions to buy stars.
- throttle_scope on 15 routes that had none (question bank without login, intro, hearts,
  notifications, tickets, plans, subscription status, orders, offers, affiliate, assistant
  history and feedback, logout).
- admin: OTPCode and Session can only be added/changed by a superuser.
- deploy.sh: integrity-checked DB backup before migrate (keeps the last 2); no migrate without it.
- docs and CLAUDE.md updated to say what is verified and what is not.

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

notifications/views.py

@@ -35,6 +35,9 @@ class NotificationMarkReadView(APIView):
     """PATCH /api/notifications/{id}/read — علامت‌گذاری یک اعلان به‌عنوان خوانده‌شده"""
 
     permission_classes = [IsAuthenticated]
+    # همان سقفِ read؛ «همه را خوانده کن» برای همین جدا ساخته شد تا ۷۵ اعلان ۷۵ درخواست نشود.
+    throttle_scope = 'read'
+    throttle_classes = [ScopedRateThrottle]
 
     # request=None لازم است: بدونِ آن spectacular نمی‌تواند بدنه‌ی PATCH را حدس
     # بزند و **کلِ ویو را از اسکیما کنار می‌گذارد** — یعنی این مسیر در قراردادی