Question packs removed at the root; all subscriptions 4 assistant questions a day; Bazaar is subscription-only

- subscription.0017/0018, payment.0013: pack plans deleted, QuestionCredit/HeartsPass models and Plan.kind /
  question_credits / hearts_days / Order.question_credits / hearts_days dropped. The only paid pack order was the
  company owner's test account (user 26).
- Assistant: no credit spending; quota is the daily cap only (free 2, every plan 4, gift subscription 4).
- Bazaar: verify_purchase is subscription-only (no inapp guess), start/purchase responses lose productType,
  verify refuses an order without a subscription. A paid order with no subscription now logs ERROR.
- Removed POST /api/payment/orders (internal; no caller). Its permission tests stay.
- Pack-based tests rewritten on subscriptions (refund, security, Bazaar token); pack-only test files deleted.
- docs: profit table for 4/day on both payment routes plus free users; handbook, operations, CLAUDE.md current.
949 tests green.

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

ai_tutor/tests_quota.py

@@ -50,4 +50,4 @@ class DailyQuotaTests(TestCase):
 
     def test_gifted_subscription_without_plan_gets_the_default(self):
         Subscription.objects.create(user_id=self.user.id, plan=None, status='active', expires_at=None)
-        self.assertEqual(ai_daily_quota(self.user.id), 15)
+        self.assertEqual(ai_daily_quota(self.user.id), 4)  # DEFAULT_SUBSCRIBER_AI_QUOTA، مثلِ پلن‌های فروشی