refactor(builder): extract useNodeProp hook, dedup StylePanel setProp boilerplate

Adopted in BackgroundSectionStylePanel, ButtonStylePanel, ContainerStylePanel,
FormStylePanel, GenericPropsEditor, HeroStylePanel, ImageStylePanel,
MediaStylePanel, NavStylePanel, SectionTypePanel, SocialStylePanel,
TextStylePanel — only where the inline setProp/setPropStyle were behaviorally
identical to the hook. PricingStylePanel and FeaturesEditor keep their own
array-mutation logic since it differs. Behavior-preserving (task E4.1).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

craft/src/panels/right/styles/ImageStylePanel.tsx

@@ -1,4 +1,4 @@
-import React, { useCallback, CSSProperties } from 'react';
+import React, { CSSProperties } from 'react';
 import { useEditor } from '@craftjs/core';
 import {
   IMAGE_RADIUS_PRESETS,
@@ -8,6 +8,7 @@ import {
   SectionLabel,
   PresetButtonGrid,
   TextInputField,
+  useNodeProp,
 } from './shared';
 import { AssetPicker } from '../../../ui/AssetPicker';
 
@@ -16,14 +17,7 @@ export const ImageStylePanel: React.FC<StylePanelProps> = ({ selectedId, nodePro
   const { actions } = useEditor();
   const style: CSSProperties = nodeProps.style || {};
 
-  const setPropStyle = useCallback(
-    (property: string, value: string) => {
-      actions.setProp(selectedId, (props: any) => {
-        props.style = { ...props.style, [property]: value };
-      });
-    },
-    [actions, selectedId],
-  );
+  const { setPropStyle } = useNodeProp(selectedId);
 
   const maxWidthPresets = [
     { label: '25%', value: '25%' },