Function query_graph_text_hybrid 

pub fn query_graph_text_hybrid(
    g: &ServeGraph,
    question: &str,
    mode: &str,
    depth: usize,
    token_budget: usize,
    context_filters: Option<&[String]>,
    dense: Option<(&StaticEmbedder, &HashMap<String, Vec<f32>>)>,
) -> String

Hybrid query: BM25 lexical + optional dense cosine, fused with RRF.

dense = Some((embedder, node_embeddings)) when a model is loaded. Without dense, falls back to BM25-only ranking (still better than pure IDF).