dsh-trace-repeat: Task Trace Recording and Replay Plugin

The `dsh-trace-repeat` plugin provides precise execution snapshots for agent development in the DSH Web environment through atomic versioning. It sequentially records immutable versions of three types—reasoning, tool, and user—along with full context metadata. By leveraging a built-in Git repository, the plugin supports materializing historical versions as worktrees and resuming execution from the “Reasoning Completed” version using the `/trace resume` command. It requires no configuration, automatically records sessions, and helps developers trace and reproduce the execution state at any point in time.