*dry-run

*dry-run marks a request as a dry-run request.

Sercrod does not implement dry-run behavior itself. The receiving API must honor the marker.

<button
  type="button"
  *post="'/api/save'"
  *keys="form"
  *dry-run
  *response="'preview'">
  Preview
</button>

Currently used by *post, *api, and *upload.