Function get_entities_needing_embedding 

pub fn get_entities_needing_embedding(
    conn: &Connection,
    entity_type: &str,
    force: bool,
) -> Result<Vec<(i64, String)>>

Get entity (id, name) pairs that need embeddings generated.

• If force is true, returns all entities of the given type.
• Otherwise, returns only entities with missing or placeholder (all-zero) vectors.