Add a shop sales dashboard with 30-day charts.

Portal Retail gets a Sales page for paid/fulfilled volume, daily bars, and top products so FEATURE_SHOP sites can see store performance without a third-party analytics tool.

Closes #7

site/shop/views.py

@@ -26,6 +26,7 @@ from shop.services import (
     save_cart,
     set_cart_qty,
 )
+from shop.stats import sales_dashboard
 
 logger = logging.getLogger(__name__)
 
@@ -222,6 +223,11 @@ def portal_stock_adjust(request, pk):
     return redirect("shop_portal:product_edit", pk=product.pk)
 
 
+@login_required
+def portal_sales(request):
+    return render(request, "shop/portal/sales.html", sales_dashboard())
+
+
 @login_required
 def portal_order_list(request):
     orders = Order.objects.all()[:200]