dsh_center-column-shift: Drag the Handle to Make Room for Right-Side Plugins

`dsh_center-column-shift` is a browser-based plugin that resolves DeepSeek Harness layout conflicts. By adding a draggable handle to the interface, it shifts the left conversation column to the left, freeing up space on the right and ensuring that plugin panels (such as recognition results and activity logs) are not obscured. The plugin supports drag-based movement, state persistence, and one-click reset, making it suitable for scenarios that require more display space.