Function promote_idle_for_lock_with_cell 

pub(super) fn promote_idle_for_lock_with_cell(
    cell: &AtomicU8,
    raw_idle_secs: u64,
    locked: Option<bool>,
    s: &Settings,
) -> u64

Cell-parameterised variant of promote_idle_for_lock so the orchestration (load → decide → log → store → promote) is testable with a local atomic — mirrors user_idle_warn_throttle above.