Function insert_document_with_chunks 

pub fn insert_document_with_chunks(
    conn: &Connection,
    doc_id: &str,
    title: &str,
    namespace: &str,
    source_path: Option<&str>,
    metadata: Option<&Value>,
    chunks: &[ChunkRow],
) -> Result<(), MemoryError>

Insert a document and all its chunks + FTS entries in a single transaction.

chunks is a vec of (content, embedding_bytes, q8_bytes, token_count_estimate).