//! Hybrid code search (BM25 + dense embeddings) over a per-repo persistent index.
//!
//! Public entry points:
//! - `Index::open(path)` / `Index::build(path)` — open or build the on-disk index
//! - `index.search(query, opts)` — hybrid retrieval + ranked top-k
//! - `index.find_related(file, line, opts)` — semantic similarity from a chunk
//!
//! The whole module is gated behind no feature flags for v1 — search is always built in.