fix: #3610525 Example booking workflow: route decision conditions on the result element (validation.result)

The example booking workflow's operator-decision flows compared the bare result variable against a scalar (validation == approved), but a comment/review task stores its outcome as a structured {result, comment} value, so the outcome lives under result. The orchestra example workflows use the dotted form (decision.result); this workflow now follows the same convention.

Seven conditions are updated: n_validate (validation.result), n_refund_review (refund_review.result) and n_attendance (attendance.result, three flows).

Not a functional break: orchestra resolves a bare result variable to its result element too (issue #3610513), so a comment/review outcome routes the same either way. This aligns the example with the documented convention and reads clearly.