dsh-code-index: DeepSeek Harness Codebase Index Plugin

dsh-code-index is a third-party plugin for DeepSeek Harness designed to provide a stable codebase map for agents, addressing the issue of models lacking key file location and symbol recognition capabilities in code repository tasks. Leveraging tree-sitter, the plugin offers symbol-based indexing, relevance-ranked symbol search, and repository maps of limited size that can be automatically updated. Core functions include `code_index` (constructing and maintaining indexes, supporting six languages such as TypeScript, Python, and Go, with incremental refresh), `code_symbols` (listing functions, classes, and other symbols along with their locations), `code_search` (sorting search results based on exact, prefix, substring, and fuzzy matching, prioritizing exported symbols), and `code_map`.