[mdjastrzebski]

Summary

Adds NaiveList, the simplest possible virtualized list. Its API is only the core props: data and renderItem({ item, index }).

• A vertical ScrollView tracks the scroll offset (onScroll, throttled to 16 ms) and the viewport height (onLayout).
• computeRenderWindow renders the items that overlap the viewport plus one viewport of buffer above and below. A top and a bottom spacer view stand in for everything else.
• Each item is wrapped in a View whose onLayout caches its height by index. A changed height triggers a re-render. Unmeasured items count as 50 px.
• Items are keyed by index, so no keyExtractor is needed.

Known limitations (by design)

• Blank areas and content jumps when scrolling fast or when the 50 px estimate is off.
• The first frame is empty until the viewport is measured.
• Cached sizes are keyed by index, so they are wrong after inserts or reorders until those items are re-measured.
• Every scroll event re-renders the whole list.

Other changes

• Removed the template multiply export.
• The example app now renders 10,000 variable-height rows with NaiveList.
• README usage section updated.
• Added yarn.lock.

Testing

• yarn typecheck, yarn lint and yarn test pass.
• Unit tests cover computeRenderWindow only. There is no React test renderer in the dev dependencies, so the component itself is untested.
• Not run on a device or simulator yet.