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>

ai_tutor/tests.py

@@ -111,9 +111,11 @@ class AskAIGenerationFailureTests(TestCase):
 
     def test_generation_failure_does_not_consume_quota_slot(self):
         # یک سوالِ ناموفق می‌فرستیم (که نباید کوتا مصرف کنه)، بعد دقیقاً
-        # DAILY_AI_QUOTA سوالِ موفق پشتِ سرِ هم می‌فرستیم؛ همه باید ۲۰۰
+        # به اندازه‌ی سقفِ روزانه سوالِ موفق پشتِ سرِ هم می‌فرستیم؛ همه باید ۲۰۰
         # بگیرن، یعنی سوالِ ناموفقِ اول اسلاتی از کوتا مصرف نکرده.
-        from .views import DAILY_AI_QUOTA
+        from .views import daily_quota
+
+        DAILY_AI_QUOTA = daily_quota(self.user.id)
 
         with patch(
             'ai_tutor.views.generate_tutor_answer',
@@ -126,7 +128,7 @@ class AskAIGenerationFailureTests(TestCase):
             ok_response = self._ask()
             self.assertEqual(ok_response.status_code, 200)
 
-        # این سوالِ اضافه باید رد بشه چون سقفِ ۱۵ (نه ۱۴) واقعاً پر شده.
+        # این سوالِ اضافه باید رد بشه چون سقف (نه یکی کمتر) واقعاً پر شده.
         throttled_response = self._ask()
         self.assertEqual(throttled_response.status_code, 429)