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/HeroStylePanel.tsx

@@ -1,5 +1,4 @@
-import React, { useCallback } from 'react';
-import { useEditor } from '@craftjs/core';
+import React from 'react';
 import {
   StylePanelProps,
   CollapsibleSection,
@@ -8,16 +7,13 @@ import {
   inputStyle,
   btnActiveStyle,
   sectionGap,
+  useNodeProp,
 } from './shared';
 import { AssetPicker } from '../../../ui/AssetPicker';
 
 /* ---------- HERO STYLE PANEL ---------- */
 export const HeroStylePanel: React.FC<StylePanelProps> = ({ selectedId, nodeProps }) => {
-  const { actions } = useEditor();
-
-  const setProp = useCallback((key: string, value: any) => {
-    actions.setProp(selectedId, (props: any) => { props[key] = value; });
-  }, [actions, selectedId]);
+  const { setProp } = useNodeProp(selectedId);
 
   const bgType = nodeProps.bgType || 'color';