dsh-done-check: Add an executable acceptance checklist for DSH

dsh-done-check is a DSH workflow plugin maintained by BeforeLanding. It writes the acceptance criteria defined by the task into `done-check.yaml`, executes commands via DSH, and records the exit code, output, execution time, and file fingerprints. Results marked as stale after code changes require re-verification, and manual items must be concluded by the developer. This article introduces environment requirements, installation commands, a three-step quick start, runnable CSV examples, four types of result semantics, command references, and precautions such as running with the current dsh process permissions, and provides the table of contents and GitHub link.