dsh-width: Adjust DSH web input and content area widths

dsh-width is a lightweight plugin for the DeepSeek Harness (DSH) web interface, designed to address interface width adjustment issues. The plugin adds a "Display" page to DSH's "Settings," providing two sliders to adjust the width percentages of the content display area and the input box respectively. The sliders are set to a range of 30% to 100% with a step of 5%, a default value of 100%, and include a reset button. Adjustments take effect immediately, and the configuration is persistently saved in the `dsh-width` section of the `~/.dsh/settings.yaml` file. It also optimizes the alignment and width synchronization of the session menu and task list. Installation supports adding from GitHub or a local directory and requires DSH version 0.1.0-rc.6 or higher; for versions 0.1.0-rc.7 and above, a restart is required after installation.