底部工具栏的子选项锚点 ref 改用查表

- src/components/image-editor/ImageCanvasBottomToolbarView.tsx：把 spec / music / model3d / publication 的三层三元 ref 选择链提成 toolWrapRefs 映射表，新增子选项时不再延长三元链

验证：npx vitest run src/components/image-editor/ImageCanvasBottomToolbarView.test.tsx（3 用例全绿）、npm run typecheck

src/components/image-editor/ImageCanvasBottomToolbarView.tsx

@@ -100,6 +100,17 @@ export function ImageCanvasBottomToolbarView({
   onOpenToolOptions,
   onCloseToolOptions,
 }: ImageCanvasBottomToolbarViewProps) {
+  // 每个可展开子选项挂在自己那一格上的定位锚点：查表比三层三元链更好加新工具。
+  const toolWrapRefs: Record<
+    ToolbarOptionTool,
+    RefObject<HTMLSpanElement | null>
+  > = {
+    spec: specToolWrapRef,
+    music: musicToolWrapRef,
+    model3d: model3dToolWrapRef,
+    publication: publicationToolWrapRef,
+  };
+
   return (
     <CanvasToolbar
       className={[
@@ -118,15 +129,7 @@ export function ImageCanvasBottomToolbarView({
             <CanvasToolbarGroup key={id}>
               {separatorBefore ? <CanvasToolbarDivider /> : null}
               <span
-                ref={
-                  id === 'spec'
-                    ? specToolWrapRef
-                    : id === 'music'
-                      ? musicToolWrapRef
-                      : id === 'model3d'
-                        ? model3dToolWrapRef
-                        : publicationToolWrapRef
-                }
+                ref={toolWrapRefs[id]}
                 className={[
                   'image-canvas-editor__bottom-toolbar-option-wrap',
                   id === 'spec' ? 'image-canvas-editor__spec-tool-wrap' : '',