Add stock management, order notifications, webhooks, expiration cron, and billet type validation

- Decrement billet quantity after purchase in BilletOrderService::generateOrderTickets
- Block purchase when stock is exhausted (quantity <= 0) in OrderController::buildOrderItems
- Add organizer email notification on new order (order_notification_orga template)
- Add organizer email notification on cancel/refund (order_cancelled_orga template)
- Add ExpirePendingOrdersCommand (app:orders:expire-pending) cron every 5min via Ansible
  - Cancels pending orders older than 30 minutes, restores stock, invalidates tickets
  - Includes BilletBuyerRepository::findExpiredPending query method
  - 3 unit tests covering: no expired orders, stock restoration, unlimited billets
- Add payment_intent.payment_failed webhook: cancels order, logs audit, emails buyer
- Add charge.refunded webhook: sets order to refunded, invalidates tickets, notifies orga and buyer
- Validate billet type (billet/reservation_brocante/vote) against organizer offer
  - getAllowedBilletTypes: gratuit=billet only, basic/sur-mesure=all types
  - Server-side validation in hydrateBilletFromRequest, UI filtering in templates
- Update TASK_CHECKUP.md: all Billetterie & Commandes items now complete

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ansible/deploy.yml

@@ -189,6 +189,13 @@
         job: "/var/backups/e-ticket/backup.sh >> /var/log/e-ticket-backup.log 2>&1"
         user: bot
 
+    - name: Configure expire pending orders cron (every 5 minutes)
+      cron:
+        name: "e-ticket expire pending orders"
+        minute: "*/5"
+        job: "docker compose -f /var/www/e-ticket/docker-compose-prod.yml exec -T php php bin/console app:orders:expire-pending --env=prod >> /var/log/e-ticket-expire-orders.log 2>&1"
+        user: bot
+
     - name: Configure messenger monitor cron (every hour)
       cron:
         name: "e-ticket messenger monitor"