refactor: 企业级目录重构与播放/关于页体验升级

- 按 app / shared / entities / features 分层，路由懒加载并抽出布局组件
- 请求层改为可插拔拦截器，统一错误类型、超时取消与端点拆分
- 抽取播放器、骨架屏、网格等复用组件，点赞收藏接入统一交互反馈
- 关于页重做为无边框极光风格，补充 iOS / Google Play 下载入口
- 修复播放页滚轮切集吞事件、页面误滚动、后台持续播放与声音记忆问题
- 语言按本地偏好与 IP 识别，国旗改为内联 SVG
- 清理未使用的旧站点文件，补充 ESLint 配置

src/shared/hooks/useEngagement.js

@@ -0,0 +1,56 @@
+// Author: fruit.com.cn
+import { useState } from 'react';
+import { engagementApi } from '../api/engagement';
+import { useMutation } from './useMutation';
+
+/**
+ * 点赞 / 收藏状态与交互，Shorts 与播放页共用。
+ * likeTargetType: 'EPISODE' | 'DRAMA'
+ */
+export function useEngagement({ likeTargetType, likeTargetId, dramaId, initialLikeCount = 0, initialSaveCount = 0 }) {
+  const [liked, setLiked] = useState(false);
+  const [likeCount, setLikeCount] = useState(Number(initialLikeCount) || 0);
+  const [saved, setSaved] = useState(false);
+  const [saveCount, setSaveCount] = useState(Number(initialSaveCount) || 0);
+  const likeMutation = useMutation(() => engagementApi.toggleLike(likeTargetType, likeTargetId));
+  const saveMutation = useMutation(() => engagementApi.toggleFavorite(dramaId));
+
+  const toggleLike = async () => {
+    try {
+      const result = await likeMutation.run();
+      setLiked(Boolean(result?.liked));
+      setLikeCount(Number(result?.count) || 0);
+    } catch {
+      // 交互失败时保持原状态，避免误导用户
+    }
+  };
+
+  const toggleSave = async () => {
+    try {
+      const next = await saveMutation.run();
+      setSaved(Boolean(next));
+      setSaveCount((count) => Math.max(0, count + (next ? 1 : -1)));
+    } catch {
+      // 同上
+    }
+  };
+
+  const syncStats = (stats) => {
+    if (!stats) return;
+    setLiked(Boolean(stats.liked));
+    setLikeCount(Number(stats.likeCount) || 0);
+    setSaved(Boolean(stats.favorited));
+    setSaveCount(Number(stats.favoriteCount) || 0);
+  };
+
+  return {
+    liked,
+    likeCount,
+    saved,
+    saveCount,
+    toggleLike,
+    toggleSave,
+    syncStats,
+    pending: likeMutation.pending || saveMutation.pending,
+  };
+}