dsh-mermaid-zoom: Add Zoom, Pan, and Copy for Mermaid Diagrams in DSH Web GUI

dsh-mermaid-zoom is a DSH plugin developed by evanfang0054 and licensed under the MIT license, specifically designed to provide browser-side interaction enhancements for Mermaid diagrams in the DSH Web GUI. Independent of host services, the plugin's main features include support for Ctrl/Cmd + scroll zoom (range 0.4x–10x), drag-to-pan, resetting the view via double-click or toolbar buttons, and exporting charts as 2x white-background PNG images. When exporting, it prioritizes the clipboard, automatically downloading if the clipboard copy fails. The plugin utilizes MutationObserver to automatically take over charts that have completed streaming rendering. Installation methods include adding it via the `dsh plugin` command for one-click setup, or manually installing the package to the profile directory and configuring `cordis.pa`