public user IDs, plans priced by tutor cost, age-based tutor tone, self-service account deletion

- profile publicId ("User482917", accounts/public_id.py); admin shows and searches it
- plans API reports aiDailyQuota per plan and freeAiDailyQuota; migration 0007 sets the
  temporary prices (monthly 99,000 / yearly 990,000 toman, 5 tutor questions a day) unless
  an admin already edited the yearly plan
- tutor tone follows the learner's age (18+ gets an adult tone at any grade); notation
  still follows the grade's book; answer cache keyed by tone (prompt tutor-v12-age-tone)
- POST /api/user/delete: phone users confirm with a fresh SMS code (same checks as login,
  now shared in verify_phone_otp), guests type "حذف"; payment records are kept, demo
  accounts refused
- delete_users --skip-paid

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

accounts/urls.py

@@ -1,6 +1,7 @@
 from django.urls import path
 
 from .views import (
+    DeleteAccountView,
     GuestSessionView,
     LoginView,
     LogoutView,
@@ -18,4 +19,5 @@ urlpatterns = [
     path('auth/logout', LogoutView.as_view(), name='auth-logout'),
     path('user/grade', SetUserGradeView.as_view(), name='user-grade'),
     path('user/profile', UserProfileView.as_view(), name='user-profile'),
+    path('user/delete', DeleteAccountView.as_view(), name='user-delete'),
 ]