mt3166/dsh-project-skills-mng: Manage project-level and global skills in the DSH right column

A DSH client plugin maintained by MT3166 that allows browsing, editing, and managing project-level and global skills in the right sidebar. It features grouping by discovery order (four levels), marked call switches and override relationships, support for creating, editing, and deleting `SKILL.md` files, filtering, viewing upstream repositories by source, checking for updates, and batch cross-layer copy and move operations, while also registering the `skills_manage` tool. The installation method provided in the README is `git clone` followed by `plugin_manager install_bundle`. It is suitable for scenarios where manual directory management becomes too costly as the number of skills increases; please check the source code and MIT license before installation.