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>

docker-compose.yml

@@ -35,6 +35,11 @@ x-app-environment: &app-environment
   # provider is connected. Never set it to a value anyone could guess.
   PAYMENT_WEBHOOK_SECRET: ${PAYMENT_WEBHOOK_SECRET:-}
   FREIGHT_ADAPTER: fake
+  # A cart the Site priced is approved at checkout and can be paid at once;
+  # orders above QUOTE_AUTO_MAX_METRES, or with a grade the Site did not
+  # compute, wait for an operator on the Kanban (app/quote_review.py).
+  QUOTE_AUTO_APPROVE: ${QUOTE_AUTO_APPROVE:-true}
+  QUOTE_AUTO_MAX_METRES: ${QUOTE_AUTO_MAX_METRES:-50}
   # Order creation in Tiny stays off until it has been tested against the
   # client's account (Tiny has no sandbox). The application credentials can be
   # set now: they let an operator connect Tiny from the Kanban, and the worker