Problem

1. Stacked timeouts with pause={false}. cycle() relied on _pause() to clear the previous timeout, but _pause is gated on the pause prop — with pause={false} every cycle() call (mouse leave, slide change) scheduled an additional timeout without clearing the previous one.
2. No cleanup on unmount. The pending cycle timeout kept running after unmount and called setActive on an unmounted component.
3. Unscoped effects. The items-count effect and the scroll listener effect had no dependency array, so the count was recomputed and the window scroll listener was removed/re-added on every render.

Changes

• Extract clearCycleTimeout() and call it unconditionally at the start of cycle(); _pause keeps its prop-gated semantics for hover.
• Clear the pending timeout in an unmount cleanup effect.
• Scope the items-count effect to [children] and register the scroll listener once ([] — the handler only touches refs and state setters).

Tests

2 new regression tests using jest.getTimerCount(): repeated mouse-leave with pause={false} does not grow the pending timer count, and unmount releases the pending cycle timeout. Both fail against main, pass with the fix. Full suite: 127 suites / 350 tests green, no snapshot changes.