dsh-plugin-reload: Reload a specific DSH plugin for Cordis Loader

`dsh-plugin-reload` is an MIT-licensed plugin for DeepSeek Harness, designed to provide a finer-grained plugin reload mechanism than restarting the host. The plugin offers the `reload_plugin` tool to the agent, allowing for the individual restart of specific Cordis Loader entries based on entry ID, module name, or MCP server name, while keeping other entries running. Core features include performing hard reloads on in-process plugins—clearing ESM/CJS caches and re-importing code from disk, with automatic rollback upon failure—and for `mcp-client` entries, restarting the MCP server subprocess and registering tools. The plugin supports three modes: `auto`, `soft`, and `hard`.