dsh-plugin-guardian: A Lifecycle Guardian Tool for DeepSeek Harness Plugins

`dsh-plugin-guardian` is designed to address conflicts, silent failures, and plugins lost after restart in the DeepSeek Harness plugin ecosystem. It provides four core functions: `plugin_doctor` for health diagnosis of a single plugin, `plugin_profile_scan` for detecting cross-plugin conflicts, `plugin_promote` for converting temporary plugins into persistent assets, and `plugin_install` for guided auditable installation. By using tiered confidence-level diagnostics and strict read/write boundary controls, it helps administrators maintain system stability and controllability during rapid plugin expansion.