dsh-at-mention: DSH Profile Bundle: Adding @-file Mentions to Composer with Prioritized Fuzzy Search and Keyboard Autocompletion

`dsh-at-mention` is a DSH plugin designed to improve the experience of referencing local files in Composer. By triggering the `@` symbol in the input box, it provides prioritized fuzzy search and keyboard completion within the current session's workspace. Key features include: limiting the search scope to the current workspace (with LRU cache support); supporting prioritized matching for exact matches, prefixes, substrings, and more; providing plain-text mention syntax (e.g., `@a @b`) to maintain cross-platform compatibility; and supporting configuration management and index rebuilding via API. The plugin supports Linux, WSL, macOS, and Windows, is easy to install, and offers developers an interactive experience similar to Claude Code.