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>

progress/serializers.py

@@ -65,3 +65,34 @@ class SelectCharacterRequestSerializer(serializers.Serializer):
 class SelectCharacterResponseSerializer(serializers.Serializer):
     characterId = serializers.CharField()
     selected = serializers.BooleanField()
+
+
+class WeeklyReportDaySerializer(serializers.Serializer):
+    date = serializers.DateField()
+    minutes = serializers.IntegerField(help_text='تخمینی؛ از فاصله‌ی رویدادها، نه زمانِ واقعیِ باز بودنِ اپ.')
+    questions = serializers.IntegerField()
+    correct = serializers.IntegerField()
+    xp = serializers.IntegerField()
+    lessons = serializers.IntegerField()
+    islands = serializers.IntegerField()
+    aiQuestions = serializers.IntegerField()
+
+
+class WeeklyReportTotalsSerializer(serializers.Serializer):
+    minutes = serializers.IntegerField()
+    activeDays = serializers.IntegerField()
+    questions = serializers.IntegerField()
+    correct = serializers.IntegerField()
+    xp = serializers.IntegerField()
+    lessons = serializers.IntegerField(help_text='درس‌های یکتا؛ تکرارِ یک درس یک بار شمرده می‌شود.')
+    islands = serializers.IntegerField(help_text='جزیره‌های یکتا.')
+    aiQuestions = serializers.IntegerField()
+
+
+class WeeklyReportResponseSerializer(serializers.Serializer):
+    today = serializers.DateField()
+    days = WeeklyReportDaySerializer(many=True, help_text='۷ روزِ آخر تا امروز، قدیمی به جدید.')
+    previousDays = WeeklyReportDaySerializer(many=True, help_text='۷ روزِ پیش از آن، قدیمی به جدید.')
+    thisWeek = WeeklyReportTotalsSerializer()
+    lastWeek = WeeklyReportTotalsSerializer()
+    streak = StreakSummarySerializer()