Adopt Orchestra's new human-task model in the example booking workflow and retire handler_url

Recent Orchestra releases retired the handler_url human-task handoff and its built-in review form, and shipped dedicated task types in their place. This brings the example booking workflow in line.

Human tasks:

• The operator validation and refund-review steps become comment_task nodes, with a note required when rejecting; the deposit-hold-failed and attendance steps become plain user nodes. The handler_url and action_title keys are dropped in favor of the node act label.
• The bespoke order-review form and its route are removed. Operators act from the inbox and the pending-actions surfaces, and the orders overview Workflow column now reads the finder per-family act URL and label.

The example workflow is also recorded with its BPMN.io diagram so it opens in the graphical modeler. Documentation and the French translation are updated. Kernel and end-to-end functional tests pass locally.