senior's post-demo changes: parent report in the student's own account, Jalali birth date, invoices, math-only tutor, priced quotas

- remove the family app from the root (separate parent accounts, invite codes, parental
  settings); progress.0006 drops its tables, permissions and migration history, and
  Profile.parent_phone, the two family notification types and ?userId= on
  /api/progress/nodes go with it
- GET /api/user/weekly-report: last 7 days next to the 7 before (estimated minutes,
  questions, accuracy, islands, tutor questions) for the "parent report" page
- profile birthDate in Jalali (accounts/jalali.py), ages 5-99, birthYear derived from it
- GET /api/payment/invoices; orders now snapshot list price and plan title
- tutor answers only math: server pre-filter, scope rule in the prompt (tutor-v11),
  refusal marker replaced with fixed text; self-harm gets a help line instead
- streamed answers now record token usage (it was always 0)
- daily tutor quota: AI_DAILY_QUOTA_FREE (default 3) vs Plan.ai_daily_quota
- delete_users management command for wiping test accounts across every app
- docs/ai-cost-and-guardrails.md: measured cost per question and guardrail results

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

subscription/views.py

@@ -23,7 +23,7 @@ from .services import has_unlimited_hearts
 
 
 class GuestAwarePurchaseThrottle(ScopedRateThrottle):
-    """همون الگوی GuestAwareAIThrottle/GuestAwareFamilyThrottle/etc: چرخشِ
+    """همون الگوی GuestAwareAIThrottle/GuestAwareDiscountThrottle/etc: چرخشِ
     حساب مهمان نباید bucket تازه‌ی purchase بده — این endpoint حساسِ مالیه
     (Subscription می‌سازه/آپدیت می‌کنه، create_order رو صدا می‌زنه). برای
     مهمان‌ها کلیدِ cache بر اساسِ IP هست، نه pk."""
@@ -84,7 +84,7 @@ class PurchaseView(APIView):
     # کلید رو می‌گیره، نه حجمِ درخواست‌های متفاوت. کاربرهای مهمان با هر
     # deviceId یک pk تازه می‌گیرن، پس کلیدِ per-user ساده قابل‌دورزدنه؛
     # GuestAwarePurchaseThrottle برای مهمان‌ها بر اساسِ IP کلید می‌سازه
-    # (مثلِ GuestAwareAIThrottle/FamilyThrottle/DiscountThrottle) و برای
+    # (مثلِ GuestAwareAIThrottle/DiscountThrottle) و برای
     # کاربرهای غیرمهمان رفتارِ per-user را حفظ می‌کنه.
     throttle_scope = 'purchase'
     throttle_classes = [GuestAwarePurchaseThrottle]
@@ -171,6 +171,7 @@ class PurchaseView(APIView):
                 subscription_id=subscription.id,
                 idempotency_key=idempotency_key,
                 plan_id=plan.id,
+                plan_title=plan.title,
             )
         except Exception:
             # Guard by pk+status+plan_id+order_id+version so this cleanup only