dsh-rescue: Rescue Mode Tool for DeepSeek Harness (DSH)

`dsh-rescue` is a rescue-mode CLI tool for DeepSeek Harness (DSH), designed to resolve issues where the GUI fails to start due to plugin conflicts. It removes third-party plugins by directly editing the manifest, forcing DSH to launch in pure core mode and allowing users to repair configuration in an isolated environment. The tool supports temporary removal, one-click restoration, transactional backup, and coordinated exit. After installation, users can enter rescue mode with `enter` to perform repairs, while the `exit` command intelligently restores the plugin stack, ensuring safe operations without affecting core functionality.