Function serve 

pub async fn serve(
    db_path: PathBuf,
    args: ServeArgs,
    app_config: &AppConfig,
) -> Result<()>

Run the HTTP memory daemon. Loads TLS state, builds AppState, spawns the GC + WAL-checkpoint loops, and binds a listener (TLS or plain HTTP).

Behaviour is preserved from the pre-W6 inline main::serve body — only the structure has changed.