Notify a rejected booking with its own message instead of the released one

On the operator-rejection path of the booking example workflow (operator validation rejected, then refund, notify and release), the customer notification reuses the "released" milestone. Its message reads "Your booking was released and is no longer held. You are welcome to book again."

That is an abandon or timeout message. It is wrong for an operator rejection: the operator declined a paid, validated-pending booking and it was refunded, so telling the customer the hold was released and they are welcome to book again misstates both the tone and the facts.

Proposed resolution

Give the rejection path its own notification rather than reusing the released one. The two events are genuinely different: released is the hold being let go (a form timeout or an abandoned payment), while rejected is the operator declining the booking.

• OrderNotifier gains a "rejected" milestone with its own message ("your booking could not be confirmed and was declined"); the refund line still appends when a payment was actually refunded.
• NotifyOrder gains a "rejected" outcome option.
• The rejection step (the notify node reached only from the reject-and-refund branch) is repointed to the "rejected" outcome and relabelled "Notify: rejected", in both the executable config and the BPMN.
• A new orchestra_booking_rejected Easy Email template; the released template stays for the abandon and timeout paths.