feat(mp): 小程序统一组件库 Phase 1 — Token 扩展 + 10 组件 + useListPage Hook

三层架构组件库：
- 第 1 层原子组件：PageShell/ContentCard/StatusTag/SectionTitle/LoadingCard
- 第 2 层组合模式：PageHeader/SearchSection/CardList/PaginationBar
- 第 3 层 Hook：useListPage（列表页通用逻辑抽象）

Token 扩展：新增 --tk-card-*/--tk-gap-*/--tk-page-* 等结构化 CSS 变量，
关怀模式通过变量覆写自动生效，新组件零额外代码即获关怀支持。

设计规格：docs/superpowers/specs/2026-05-16-miniprogram-unified-components-design.md

apps/miniprogram/src/components/ui/LoadingCard/index.tsx

@@ -0,0 +1,47 @@
+import { View } from '@tarojs/components';
+import './index.scss';
+
+interface LoadingCardProps {
+  count?: number;
+  layout?: 'card' | 'list' | 'detail';
+}
+
+const LoadingCard: React.FC<LoadingCardProps> = ({
+  count = 3,
+  layout = 'card',
+}) => {
+  return (
+    <View className={`loading-card-group loading-card-group--${layout}`}>
+      {Array.from({ length: count }, (_, i) => (
+        <View key={i} className="loading-card">
+          {layout === 'card' && (
+            <>
+              <View className="loading-card__line loading-card__line--title" />
+              <View className="loading-card__line loading-card__line--text" />
+              <View className="loading-card__line loading-card__line--short" />
+            </>
+          )}
+          {layout === 'list' && (
+            <View className="loading-card__row">
+              <View className="loading-card__circle" />
+              <View className="loading-card__lines">
+                <View className="loading-card__line loading-card__line--title" />
+                <View className="loading-card__line loading-card__line--short" />
+              </View>
+            </View>
+          )}
+          {layout === 'detail' && (
+            <>
+              <View className="loading-card__line loading-card__line--title" />
+              <View className="loading-card__line loading-card__line--text" />
+              <View className="loading-card__line loading-card__line--text" />
+              <View className="loading-card__line loading-card__line--short" />
+            </>
+          )}
+        </View>
+      ))}
+    </View>
+  );
+};
+
+export default React.memo(LoadingCard);