DeepSeek Harness Plugin: semantic-search Local Semantic Code Search

`semantic-search` is a local semantic code search plugin developed for DeepSeek Harness (DSH), designed to overcome the limitation of traditional keyword matching in understanding code semantics through vector indexing. It supports over 16 programming languages and offers core features such as offline embedding, hybrid retrieval (vector + BM25), and incremental updates. The plugin enables efficient code snippet retrieval without requiring an internet connection, significantly improving development and debugging efficiency.