继续沉淀结果页返回按钮

新增共享 PlatformBackActionButton 承接结果页轻量返回入口
将拼图方洞拼消消视觉小说等结果页返回按钮收口到共享组件
将拼消消跳一跳敲木鱼宝贝识物结果页返回按钮收口到共享组件
补充对应测试并更新 PlatformUiKit 收口计划与共享决策记录

src/components/common/PlatformBackActionButton.tsx

@@ -0,0 +1,58 @@
+import type { ButtonHTMLAttributes } from 'react';
+
+import { ArrowLeft } from 'lucide-react';
+
+import { PlatformActionButton } from './PlatformActionButton';
+import type { PlatformActionButtonSurface } from './platformActionButtonModel';
+
+type PlatformBackActionButtonVariant = 'compact' | 'regular';
+
+type PlatformBackActionButtonProps = Omit<
+  ButtonHTMLAttributes<HTMLButtonElement>,
+  'children'
+> & {
+  label?: string;
+  variant?: PlatformBackActionButtonVariant;
+  surface?: PlatformActionButtonSurface;
+};
+
+const VARIANT_CLASS: Record<PlatformBackActionButtonVariant, string> = {
+  compact: 'gap-1.5 py-1.5 text-[11px]',
+  regular: 'gap-2 py-2 text-sm',
+};
+
+const ICON_CLASS: Record<PlatformBackActionButtonVariant, string> = {
+  compact: 'h-3.5 w-3.5',
+  regular: 'h-4 w-4',
+};
+
+/**
+ * 平台轻量返回动作按钮。
+ * 统一结果页、工作台等白底场景里的“左箭头 + 返回文案”按钮骨架。
+ */
+export function PlatformBackActionButton({
+  label = '返回',
+  variant = 'compact',
+  surface = 'platform',
+  className,
+  ...buttonProps
+}: PlatformBackActionButtonProps) {
+  return (
+    <PlatformActionButton
+      {...buttonProps}
+      surface={surface}
+      tone="ghost"
+      size="xs"
+      className={[
+        'min-h-0 self-start',
+        VARIANT_CLASS[variant],
+        className,
+      ]
+        .filter(Boolean)
+        .join(' ')}
+    >
+      <ArrowLeft className={ICON_CLASS[variant]} />
+      {label}
+    </PlatformActionButton>
+  );
+}