#4685 Docs: show the guard result on guarded skipped lines in make-workflows-idempotent

The log-mode skipped-step line for a guarded step now ends with what the guard returned (swamp-club#4682): main │ skipped provision (guarded) · guard: → . A list or map result shows as a count such as [3 items] or {2 keys}; text is quoted, escaped and cut short.

content/manual/how-to/make-workflows-idempotent.md shows the old line in three examples (the single-step provision example and the two forEach provision- lines). Each data.latest guard there returns a whole record, so the new suffix is → {N keys}. Update the examples, and consider one sentence saying the value after the arrow is truthy because only a truthy guard skips.