Function use_cleanup 

pub fn use_cleanup<F>(cleanup: F)
where
    F: FnOnce() + 'static,

Registers a cleanup callback that will be executed when the current hook context is cleared (e.g., when a match arm switches).

This is useful for cleaning up side effects like intervals, timeouts, or subscriptions that are not automatically managed by signals.

The cleanup callback is only registered once on the first render. On subsequent re-renders at the same hook index, this is a no-op.

Arguments

• FnOnce() + 'static - The cleanup callback to execute on context teardown.