dsh-disk-audit: DeepSeek Harness Data Directory Disk Usage Audit

`dsh-disk-audit` is a disk usage audit plugin for DeepSeek Harness (dsh), designed to address the issue of undetected disk space growth in data directories. It provides audit capabilities for total size, directory distribution, largest files, and cleanup recommendations. The plugin is dependency-free and read-only, and can be invoked via CLI tools or an Agent, effectively helping users monitor log growth and preventing storage from being filled up.