dsh-pixel-print: Pixel Print Size Calculation

The `dsh-pixel-print` plugin for DeepSeek Harness (DSH) follows the “everything is a plugin” philosophy and focuses on providing lightweight pixel-print size calculations. Maintained by uckkk under the MIT license, it registers a tool named `pixel_print` that returns precise calculation results when invoked with parameters. Implemented in pure Node.js and requiring no internet connection, it is ready to use in DSH sessions after installation. Developers should ensure that their environment includes the specified dependencies, and they are advised to review the source code and license.