dsh-file-quote: Unified Quoting Plugin for DeepSeek Harness

`dsh-file-quote` is a plugin tool in the DeepSeek Harness ecosystem designed to address the issues of excessive space usage and unclear context relevance when quoting files or code in conversations. Built on `dsh-better-sidebar`, it allows users to select text and generate quote blocks that include file paths and line ranges. Once generated, the quote block is displayed as a collapsed Chip on the client side, while it is rendered as complete Markdown quote content when sent to the AI. It supports insertion at any position, multiple quotes that remain separate from one another, and clicking to jump back to the original source. During installation, users should install the core dependencies first and handle any potential build script blocking issues.