llm-wiki-sidebar: LLM Wiki Workspace in the DSH Sidebar

`llm-wiki-sidebar` is a DeepSeek Harness plugin that extends the built-in sidebar into a Wiki workbench. It supports browsing Markdown Wikis in the sidebar, with clickable `[[wikilinks]]`, provenance links, backlinks, and source-code previews. The plugin includes a built-in Wiki Lint tool, supports managing multiple Wikis, and bundles the `llm-wiki` agent skill. After installation, a restart is required, and any conflicting third-party sidebar plugins should be removed.