xby-char-index: A Character-Index-Based String Manipulation Protocol Server

The `xby-char-index` plugin for DeepSeek Harness (DSH) provides a protocol server for character-index-based string operations. It supports API key management, character and substring location (including the nth occurrence and all indices), precise string editing (such as splitting, insertion, and replacement), regular expression matching extraction, and character statistics. It is suitable for scenarios requiring high-precision character control, test code generation, or complex data cleansing. Users can install it via the command line and configure the API key.