feat: approve priced carts at checkout so customers can pay at once

Every quote waited for an operator before it could be paid, so an order
placed at night waited for the morning. A cart the Site priced is now
approved when the quote is created, through the same server pricing the
operator's approval uses (app/quote_review.py). Orders above
QUOTE_AUTO_MAX_METRES (50 m) and items claiming a discount on art the Site
could not analyse still wait for review; the Kanban shows which quotes were
approved automatically and why the others wait.

The grade is still computed in the browser (roadmap 3.2, 3.9), so the
discount remains a customer-supplied value until the server computes it.

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

tests/payment_test.py

@@ -12,7 +12,7 @@ from urllib.error import HTTPError
 from urllib.request import Request, urlopen
 from uuid import uuid4
 
-from tests.smoke_test import BASE, Client, upload_bytes, item_spec, with_host
+from tests.smoke_test import BASE, Client, approved_quote, upload_bytes, item_spec, with_host
 
 SECRET = os.environ.get('PAYMENT_WEBHOOK_SECRET', 'local-webhook-secret').encode()
 
@@ -42,8 +42,7 @@ def reviewed_quote():
                'mail': 'payment-' + uuid4().hex[:8] + '@example.test'}
     quote = customer.call('/quotes', {'request_key': str(uuid4()), 'customer': profile,
                                       'items': [item], 'freight': {'service': 'pickup'}})
-    approved = customer.call('/operator/quotes/' + quote['id'] + '/approve',
-                             {'items': [item]}, operator=True)
+    approved = approved_quote(customer, quote, [item])
     return customer, quote['id'], approved['total_cents']