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>

accounts/tests_birth_date.py

@@ -0,0 +1,90 @@
+"""
+تاریخِ تولدِ شمسی در پروفایل (۲۰۲۶-۱۰-۰۱). اپ روز/ماه/سالِ شمسی می‌فرستد؛ سرور
+میلادی ذخیره می‌کند و birthYear را از آن می‌سازد. راه‌های شکستن: تاریخِ ناموجود
+(۳۰ اسفندِ غیرکبیسه)، ارقامِ فارسی، سنِ خارج از بازه، و جدا افتادنِ سال از تاریخ.
+"""
+from datetime import date
+
+from django.core.cache import cache
+from django.test import SimpleTestCase, TestCase
+from rest_framework.test import APIClient
+
+from accounts import jalali
+from accounts.authentication import issue_access_token
+from accounts.models import Profile, User
+
+
+class JalaliConversionTests(SimpleTestCase):
+    KNOWN = [
+        ((1405, 1, 1), date(2026, 3, 21)),
+        ((1403, 12, 30), date(2025, 3, 20)),   # اسفندِ کبیسه
+        ((1404, 12, 29), date(2026, 3, 20)),   # آخرین روزِ سالِ غیرکبیسه
+        ((1385, 4, 12), date(2006, 7, 3)),
+        ((1367, 10, 11), date(1989, 1, 1)),
+    ]
+
+    def test_known_dates_both_ways(self):
+        for jalali_date, gregorian in self.KNOWN:
+            self.assertEqual(jalali.to_gregorian(*jalali_date), gregorian)
+            self.assertEqual(jalali.from_gregorian(gregorian), jalali_date)
+
+    def test_thirtieth_of_esfand_exists_only_in_leap_years(self):
+        self.assertTrue(jalali.is_leap(1403))
+        self.assertFalse(jalali.is_leap(1404))
+        with self.assertRaises(ValueError):
+            jalali.to_gregorian(1404, 12, 30)
+
+    def test_every_day_of_a_century_round_trips(self):
+        start = date(1940, 1, 1).toordinal()
+        for offset in range(0, 36600, 7):
+            day = date.fromordinal(start + offset)
+            self.assertEqual(jalali.to_gregorian(*jalali.from_gregorian(day)), day)
+
+    def test_persian_digits_and_slashes_are_accepted(self):
+        self.assertEqual(jalali.parse('۱۳۸۵/۰۴/۱۲'), date(2006, 7, 3))
+
+
+class ProfileBirthDateApiTests(TestCase):
+    def setUp(self):
+        cache.clear()
+        self.user = User.objects.create(device_id='birth-date-device', is_guest=True)
+        self.client = APIClient()
+        self.client.credentials(HTTP_AUTHORIZATION=f'Bearer {issue_access_token(self.user.id)}')
+
+    def patch(self, body):
+        return self.client.patch('/api/user/profile', body, format='json')
+
+    def test_date_is_stored_and_returned_in_jalali_with_its_year(self):
+        response = self.patch({'birthDate': '1385-04-12'})
+        self.assertEqual(response.status_code, 200, response.content)
+        self.assertEqual(response.json()['birthDate'], '1385-04-12')
+        self.assertEqual(response.json()['birthYear'], 1385)
+        self.assertEqual(Profile.objects.get(user=self.user).birth_date, date(2006, 7, 3))
+        self.assertEqual(self.client.get('/api/user/profile').json()['birthDate'], '1385-04-12')
+
+    def test_adults_are_accepted(self):
+        self.assertEqual(self.patch({'birthDate': '1360-01-15'}).status_code, 200)
+
+    def test_impossible_dates_are_rejected(self):
+        for bad in ('1404-12-30', '1385-13-01', '1385-07-31', '1385-4', 'دیروز'):
+            self.assertEqual(self.patch({'birthDate': bad}).status_code, 400, bad)
+
+    def test_future_and_too_young_or_old_are_rejected(self):
+        for bad in ('1410-01-01', '1403-01-01', '1300-01-01'):
+            self.assertEqual(self.patch({'birthDate': bad}).status_code, 400, bad)
+
+    def test_date_and_year_together_are_ambiguous(self):
+        self.assertEqual(self.patch({'birthDate': '1385-04-12', 'birthYear': 1390}).status_code, 400)
+
+    def test_a_different_year_alone_clears_the_old_date(self):
+        self.patch({'birthDate': '1385-04-12'})
+        data = self.patch({'birthYear': 1388}).json()
+        self.assertEqual((data['birthYear'], data['birthDate']), (1388, None))
+
+    def test_null_clears_the_date(self):
+        self.patch({'birthDate': '1385-04-12'})
+        data = self.patch({'birthDate': None}).json()
+        self.assertEqual((data['birthYear'], data['birthDate']), (None, None))
+
+    def test_parent_phone_is_gone(self):
+        self.assertNotIn('parentPhone', self.client.get('/api/user/profile').json())