Migration from older versions

Detect and upgrade pre-v8 react-horizontal-scrolling-menu patterns that agents trained on older data still generate: destructured visibleElements/isFirstItemVisible/isLastItemVisible/initComplete (removed v6), Separator items, separatorClassName and getPrevItem/getNextItem (removed v7), the Arrows prop (removed v3), missing dist/styles.css import (required since v4), CJS require of the ESM-only package (v5), transitionDuration/transitionBehavior silently ignored after the v8 noPolyfill flip, the misleading 8.1.0 changelog BREAKING block, and >=8.2.2 for TypeScript moduleResolution node16/bundler. Load when upgrading versions or whenever generated or reviewed code uses any…