[iOS] Re-sync layer opacity and transform from retained props when recycling buttons (#4360)

## Description

On Fabric, a v3 `Pressable` (or any `RNGestureHandlerButton`) with a
style opacity rendered correctly on first mount, but lost the opacity
once the component was unmounted and mounted again - the remount reuses
a recycled native view and the button renders fully opaque.

The root cause is a desync between the wrapper's layer and its retained
props, introduced by the recycle reset from #4131:

- `RNGestureHandlerButton.prepareForRecycle` resets `target.alpha = 1.0`
to clear residual press-animation state, but target is the
`animationTarget` - the wrapper `RNGestureHandlerButtonComponentView`,
whose `layer.opacity` carries React's style opacity.
- Fabric retains `_props` across recycling, and
`RCTViewComponentView.updateProps`: re-applies opacity only when it
differs from the retained props.
- Even when another prop change triggers `invalidateLayer` (which would
re-apply the correct opacity unconditionally), our `finalizeUpdates:`
save/restore detects that as an unwanted change and restores the stale
value.

The fix re-syncs the layer from the retained props right after the
button reset in `prepareForRecycle`, instead of leaving neutral values:
`opacity` from `viewProps.opacity`, `transform` via
`viewProps.resolveTransform(_layoutMetrics)`.

> [!NOTE]
> The transform gets the same treatment: the identity reset leaves the
layer desynced from the retained props in the same way, it just isn't
visible today because `updateLayoutMetrics` happens to recompute
transforms after recycling. Re-syncing removes the reliance on that
implementation detail.

Fixes #4353

## Test plan

<details>
<summary>Tested on the following code:</summary>

```tsx
import React, { useState } from 'react';
import { Button, StyleSheet, Text, View } from 'react-native';
import { Pressable } from 'react-native-gesture-handler';

// Repro for #4353
// iOS + Fabric: style opacity (and transform) on a v3 Pressable is applied on
// the first mount, but lost after the component is unmounted and mounted again
// (the remount reuses a recycled native view). The plain Views on the right
// show the expected rendering and should stay identical to the Pressables
// after every toggle.

export default function EmptyExample() {
  const [mounted, setMounted] = useState(true);
  const [generation, setGeneration] = useState(0);

  return (
    <View style={styles.container}>
      <Button
        title={mounted ? 'Unmount' : 'Mount again'}
        onPress={() => {
          setMounted(!mounted);
          if (!mounted) {
            setGeneration(generation + 1);
          }
        }}
      />
      <Text style={styles.caption}>
        Remounts: {generation} — left column: Pressable, right column: expected
        (plain View)
      </Text>

      <View style={styles.row}>
        {mounted ? (
          <Pressable
            style={[styles.box, styles.opacityStyle]}
            onPress={() => console.log('press (opacity)')}>
            <Text style={styles.label}>opacity: 0.3</Text>
          </Pressable>
        ) : (
          <View style={styles.boxPlaceholder} />
        )}
        <View style={[styles.box, styles.opacityStyle]}>
          <Text style={styles.label}>opacity: 0.3</Text>
        </View>
      </View>

      <View style={styles.row}>
        {mounted ? (
          <Pressable
            style={[styles.box, styles.transformStyle]}
            onPress={() => console.log('press (transform)')}>
            <Text style={styles.label}>rotate: 25deg</Text>
          </Pressable>
        ) : (
          <View style={styles.boxPlaceholder} />
        )}
        <View style={[styles.box, styles.transformStyle]}>
          <Text style={styles.label}>rotate: 25deg</Text>
        </View>
      </View>
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    gap: 24,
  },
  row: {
    flexDirection: 'row',
    gap: 48,
  },
  box: {
    width: 120,
    height: 120,
    backgroundColor: 'mediumpurple',
    justifyContent: 'center',
    alignItems: 'center',
  },
  boxPlaceholder: {
    width: 120,
    height: 120,
  },
  opacityStyle: {
    opacity: 0.3,
  },
  transformStyle: {
    transform: [{ rotate: '25deg' }],
  },
  caption: {
    marginHorizontal: 24,
    textAlign: 'center',
    opacity: 0.5,
  },
  label: {
    color: 'white',
  },
});
```

</details>

Author: m-bert

packages/react-native-gesture-handler/apple/RNGestureHandlerButtonComponentView.mm

@@ -131,6 +131,17 @@ - (void)prepareForRecycle
 
   [_buttonView prepareForRecycle];
 
+  // The reset above forces this wrapper's alpha and transform back to neutral
+  // values, but Fabric retains `_props` across recycling and `updateProps:`
+  // re-applies opacity/transform only when they differ from the retained
+  // props. Re-sync the layer from the retained props so the next mount's diff
+  // stays valid (the same approach RN takes for Animated-managed props in its
+  // `prepareForRecycle`); otherwise a remount with an unchanged style opacity
+  // keeps the neutral 1.0 instead (https://github.com/software-mansion/react-native-gesture-handler/issues/4353).
+  const auto &viewProps = static_cast<const ViewProps &>(*_props);
+  self.layer.opacity = (float)viewProps.opacity;
+  self.layer.transform = RCTCATransform3DFromTransformMatrix(viewProps.resolveTransform(_layoutMetrics));
+
   // Force the next updateProps: to re-run applyStartAnimationState even if
   // the new mount's defaults match the previous mount's.
   _needsAnimationStateReset = YES;