DSH updater + official docs sync plugin

Key features

• dsh-updater-npm is a DSH updater + official docs sync plugin for DeepSeek Harness
• after the update a "Restart DSH" button appears — it exits the current process and relaunches with the original command line (PowerShell on Windows, /bin/sh on macOS/Linux
• also shown after source-tree updates and deployment repair).
• DSH Docs (official)incrementally sync deepseek-ai/deepseek-harness docs/ to $DSH_HOME/docs-sync/ (skips unchanged files by GitHub blob sha) with a progress bar, plus dsh_docs_search / dsh_docs_read model tools for in-conversation doc lookup.
• i18nUI and host messages support Chinese / English, following the system language automatically (or the manual choice in Settings → General → Language)