feat: Reanimated shared value → Rive property binding

[mfazekas]

Summary

• Added playIfNeeded() to make sure rive graphics is not in steady state after update
• Adds example demonstrating driving Rive properties from Reanimated shared values
• Uses NitroModules.box() to share ViewModelNumberProperty with worklets
• Updates happen synchronously on UI thread - no async bridging

How it works

const boxedProperty = useMemo(() => {
  const posYProperty = instance.numberProperty('posY');
  return NitroModules.box(posYProperty);
}, [instance]);

useAnimatedReaction(
  () => progress.value,
  (value) => {
    'worklet';
    const property = boxedProperty.unbox() as ViewModelNumberProperty;
    property.value = value;  // Direct setter on UI thread!
   }
);

Test plan

• Run the "Reanimated Shared Value" example
• Blue circle (React Native) and red circle (Rive) should animate in sync

In slow motion there is up to 1 frame difference:

[HayesGordon]

Nice!