Function apply_natural_language 

pub fn apply_natural_language(
    primary: Vec<SttpNode>,
    lexical_matches: Vec<SttpNode>,
    has_query_embedding: bool,
) -> (Vec<SttpNode>, bool)

Place lexical hits ahead of the primary ranking.

Without a query embedding, lexical hits replace resonance order. With an embedding, hits are prepended and the hybrid tail is kept.