Issue #3612576: Attach order tickets to the Orchestra confirmation notification (yoyaku_ticket_orchestra)

Adds the yoyaku_ticket_orchestra bridge: an order's tickets are attached to the Orchestra notification that confirms it (the confirmation email), so a booker gets one email with the PDFs rather than a separate ticket message.

How

A single event subscriber on OrchestraNotificationEvent: when the notification carries an order (the order notifier puts it in the token data), it adds one PDF ticket per confirmed booking via the notification's addAttachment(). It runs at the default priority, so the delivery channels (subscribed at OrchestraNotificationEvent::DELIVERY_PRIORITY) send the tickets with the message.

It gates purely on the ticket builder: an order with nothing to ticket (a released or cancelled order has no confirmed bookings) yields no documents, so only the confirmation notification ends up carrying tickets, with no milestone or type coupling, and no change to the order notifier.

Tests

Unit coverage for the subscriber: attaches one PDF per ticket when an order is present, nothing when no order, nothing when the order has no tickets.

Dependencies

Requires the enrichable-attachment API from orchestra #3612575 (addAttachment() / DELIVERY_PRIORITY). Follow-up to #3611638.