@choi-p/dsh-footer-order: Change DSH Web sidebar bottom items to vertically stacked and sorted.

`@choi-p/dsh-footer-order` is a layout plugin for the DeepSeek Harness (DSH) web interface, designed to address the overcrowding issue when multiple plugins register to the `sidebar.footer.action` slot simultaneously. The plugin modifies the rendering anchor from `display: contents` to a vertical flex stack, supports configuring entry order, layout modes (column, row, contents), spacing, and alignment, is compatible with empty entries, and supports configuration hot-reloading. Users can install the plugin via DSH settings or the command line (`dsh plugin add`) and adjust parameters in real-time in the settings card without requiring a restart. The default configuration is a vertical stack (`layout: column`).