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>

payment/models.py

@@ -19,7 +19,13 @@ class Order(models.Model):
     # بود و با شروعِ یک خریدِ دیگر عوض می‌شد: پرداختِ سفارشِ ماهانه بعد از
     # شروعِ خریدِ سالانه، اشتراکِ سالانه می‌داد (بازتولید شد، ۲۰۲۶-۰۹-۲۵).
     plan_id = models.IntegerField(null=True, blank=True)  # ارجاع سبک به subscription.Plan
+    # مبلغی که باید پرداخت شود؛ کدِ تخفیف همین را کم می‌کند (discount/views.py).
     amount = models.PositiveIntegerField()
+    # عکسِ لحظه‌ی خرید برای فاکتور: قیمتِ پایه پیش از تخفیف و نامِ پلن. بدونِ این،
+    # فاکتورِ ماهِ پیش با عوض شدنِ قیمت یا نامِ پلن در ادمین عوض می‌شد. سفارش‌های
+    # پیش از ۲۰۲۶-۱۰-۰۱ این دو را ندارند (null / خالی).
+    list_price = models.PositiveIntegerField(null=True, blank=True)
+    plan_title = models.CharField(max_length=50, blank=True)
     currency = models.CharField(max_length=10, default='IRT')
     status = models.CharField(max_length=10, choices=STATUS_CHOICES, default='pending')
     provider = models.CharField(max_length=10, choices=PROVIDER_CHOICES, default='gateway')