dock: DSH Web Workbench Basic Plugin

dock is a foundational workbench plugin within the DSH Web environment, maintained by AKS1st and licensed under the MIT License. It provides a VSCode-style layout shell, including an Activity Bar, Sidebar, Multi-tab Editor Area, and Status Bar. It also supports docking at the four sides of the screen and floating window mode, with layout information persisted via localStorage. The core mechanism utilizes the `ctx.workbench` registry, allowing functional plugins to mount panels, editor views, activity items, status items, and commands, thereby realizing a unified workbench mounting mechanism. dock itself is solely responsible for the shell and does not include specific functions such as file browsing, text editing, image/Markdown viewing, or Git management; these capabilities must be installed via the dock series plugins (e.g., dock-files, dock-editor) as needed.