dsh-skills-manager-plus: DeepSeek Harness Skills and Commands Management Plugin

The `dsh-skills-manager-plus` plugin provides a visual skills and command management interface for DeepSeek Harness. Through a frontend hot-apply switch, users can edit, delete, add, or install skills (compressed packages supported) and manage frequently used commands without restarting the service. The plugin operates directly on the file system, supports multiple languages, and includes local request security restrictions and an atomic write mechanism. It is suitable for users who need to adjust skill configurations frequently.