Function populate_incremental_for_paths 

pub async fn populate_incremental_for_paths(
    conn: &Connection,
    config: &EmbeddingsConfig,
    changed_paths: &[String],
    head_commit: Option<&str>,
    repo_root: Option<&Path>,
    db_path: Option<&Path>,
) -> Result<PopulateStats>

Incremental re-embedding for a set of changed file paths.

Called by the daemon after incremental_refresh when embeddings.enabled is true. Deletes old embeddings for each changed path, then re-embeds symbols and markdown docs in those files. Lightweight – no VACUUM, no full table drop.