dsh-plugin-delete-chat: Permanently delete a session in DSH

This plugin adds a "Delete chat" action to the "..." menu of every session in DeepSeek Harness Web UI. After confirmation via a dialog box, it permanently deletes the session log directory and derived cache. It stops ongoing turns, subagents, background jobs, and scheduled reminders before deletion. Once the process is complete, the sidebar row is immediately removed, and workspace files are not touched. The action can only be triggered by users from the UI; agents cannot invoke it. The article provides three installation methods: adding the package name, adding the plugin market index source, and installing from the source directory. It also covers considerations such as environment requirements (DSH ≥ 0.2.1-rc.5), uninstallation methods, irreversible deletion, execution permissions, and Host-side service dependencies.