Make order tokens resolve in Orchestra workflow messages, and show the order summary on booking confirmation

Follow-up to #3613003.

Makes [yoyaku-order:*] tokens resolve in Orchestra message interactions (and any Orchestra text tied to a booking instance). A hook_tokens bridge in yoyaku_orchestra_order resolves the instance's correlated order and re-dispatches the order tokens, mirroring how OrderNotifier already feeds the order to notification tokens; the base order tokens stay unaware of Orchestra and Orchestra stays unaware of orders.

Adds [yoyaku-order:bookings] (the grouped order summary) to the example workflow's booking-confirmation message, so the summary shows on the confirmation page.

Includes a kernel test and README docs. phpcs, phpstan and cspell clean; kernel test green.