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/shared.tsx

@@ -288,6 +288,18 @@ export interface StylePanelProps {
   nodeProps: Record<string, any>;
 }
 
+/* ---------- useNodeProp ----------
+   Shared setProp/setPropStyle boilerplate repeated across many *StylePanel.tsx
+   files. Only adopted where a panel's inline definitions were byte-equivalent
+   to this (some panels use different param names or extra logic and keep
+   their own local versions). */
+export function useNodeProp(selectedId: string) {
+  const { actions } = useEditor();
+  const setProp = useCallback((key: string, value: any) => actions.setProp(selectedId, (p: any) => { p[key] = value; }), [actions, selectedId]);
+  const setPropStyle = useCallback((prop: string, value: string) => actions.setProp(selectedId, (p: any) => { p.style = { ...p.style, [prop]: value }; }), [actions, selectedId]);
+  return { setProp, setPropStyle };
+}
+
 /* ---------- Array Prop Editor (reusable for features, items, plans, etc.) ---------- */
 interface ArrayPropEditorProps {
   selectedId: string;