Audit fixes 2026-10-03: seed keeps admin edits, plan cache, refresh limit, payment and tutor guards

- seed_content no longer undoes admin work: a SeedRecord ledger (content/seed_sync.py)
  stops deleted/renamed/re-worded content from being recreated and keeps admin-edited
  lesson text; new rows in the seed files still arrive (migration content.0010)
- plan list cache is invalidated on Plan save (receiver used a stale 'v1' key)
- token refresh per-IP cap 30/hour -> 600/hour (TOKEN_REFRESH_IP_RATE)
- a failed gateway result only changes a pending order (forged NOK no longer
  overwrites refunded/canceled)
- tutor gets the correct answer only after the student has answered
- support reply notification moved to a TicketMessage post_save signal
- global daily cap on paid AI questions (AI_GLOBAL_DAILY_MAX, default 3000)
- Bazaar verify uses only the order's SKU; bazaar orders require a SKU
- /api/health warns on the committed signing key; deploy.sh saves local commits;
  400 for bad ?unit= / ?period=; account delete keeps the referrer's Conversion
- earlier today: no stub answers outside DEBUG, ?grade= removed, logged fallbacks

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

payment/tests_refund.py

@@ -175,3 +175,24 @@ class OrderAdminTests(_Base):
         page = self.admin.get(f'/admin/payment/order/{order.pk}/change/')
         self.assertEqual(page.status_code, 200)
         self.assertNotContains(page, 'name="status"')
+
+
+class ForgedFailureCallbackTests(TestCase):
+    """
+    کال‌بکِ زرین‌پال بی‌احراز است. Status=NOKِ جعلی نباید سفارشِ بازپرداخت‌شده یا لغوشده را
+    «ناموفق» کند (تا ۲۰۲۶-۱۰-۰۳ می‌کرد و ردِ بازپرداخت از وضعیتِ سفارش می‌رفت).
+    """
+
+    def test_nok_does_not_overwrite_refunded_or_canceled(self):
+        for status in ('refunded', 'canceled'):
+            order = Order.objects.create(user_id=1, amount=1000, status=status,
+                                         gateway_authority=f'A-{status}', idempotency_key=f'k-{status}')
+            APIClient().get('/api/payment/zarinpal/callback', {'Authority': f'A-{status}', 'Status': 'NOK'})
+            order.refresh_from_db()
+            self.assertEqual(order.status, status)
+
+    def test_nok_still_fails_a_pending_order(self):
+        order = Order.objects.create(user_id=1, amount=1000, gateway_authority='A-p', idempotency_key='k-p')
+        APIClient().get('/api/payment/zarinpal/callback', {'Authority': 'A-p', 'Status': 'NOK'})
+        order.refresh_from_db()
+        self.assertEqual(order.status, 'failed')