Function run_via_pipes 

async fn run_via_pipes(
    args: &Args,
    command: &str,
    mps: Option<&WpsClient>,
    buffered: Arc<Mutex<Vec<u8>>>,
    bash: &Path,
) -> Result<i32>

Pipe-backed run path. Safety net for environments where PTY allocation fails (CI, sandboxes). Same byte semantics as the old pipe-only wrapper.