feat: add useRiveList hook

[mfazekas]

Summary

• Adds useRiveList hook for managing list properties, aligned with rive-react API
• Adds useViewModelInstance hook that works with RiveFile, ViewModel, and RiveViewRef
• Adds required option to useViewModelInstance for Error Boundary support
• Adds MenuList example demonstrating list manipulation

useRiveList API

const { length, getInstanceAt, addInstance, addInstanceAt, removeInstance, removeInstanceAt, swap, error } = useRiveList('items', viewModelInstance);

useViewModelInstance API

// From RiveFile (get default instance) - recommended
const { riveFile } = useRiveFile(require('./animation.riv'));
const instance = useViewModelInstance(riveFile);
<RiveView file={riveFile} dataBind={instance} ... />

// From RiveViewRef (get auto-bound instance)
const { riveViewRef, setHybridRef } = useRive();
const instance = useViewModelInstance(riveViewRef);

// With required: true (throws if null, use with Error Boundary)
const instance = useViewModelInstance(riveFile, { required: true });
// TypeScript knows instance is non-null

Example Pattern

function MenuList({ file }: { file: RiveFile }) {
  const instance = useViewModelInstance(file, { required: true });
  return <MenuListContent file={file} instance={instance} />;
}

Test plan

• MenuListExample uses useRiveList and useViewModelInstance(file, { required: true })

[HayesGordon]

LGTM!

[HayesGordon]

LGTM!