Module code_search 

CodeSearch tool: hybrid BM25 + vector semantic search.

Two modes:

1. BM25 only (default): tantivy full-text search. No API calls.
2. BM25 + Vector: BM25 candidates merged with HNSW vector k-NN search backed by the cersei-embeddings crate (Gemini / OpenAI / custom).

Structs

CodeSearchTool