fix: 修复代码审查发现的所有 bug

Critical 级别:
- zhipu.ts: 添加 API 响应边界检查
- DictionaryClient.tsx: 添加 entries 数组边界检查
- subtitleParser.ts: 修复 getNearestIndex 逻辑错误

High 级别:
- text-speaker/page.tsx: 修复非空断言和 ref 检查
- folder-repository.ts: 添加 user 关系 null 检查

Medium 级别:
- InFolder.tsx: 修复 throw result.message 为 throw new Error()
- localStorageOperators.ts: 返回类型改为 T | null，添加 schema 验证
- SaveList.tsx: 处理 data 可能为 null 的情况

src/modules/folder/folder-repository.ts

@@ -192,8 +192,8 @@ export async function repoGetPublicFolders(
     visibility: folder.visibility,
     createdAt: folder.createdAt,
     userId: folder.userId,
-    userName: folder.user.name,
-    userUsername: folder.user.username,
+    userName: folder.user?.name ?? "Unknown",
+    userUsername: folder.user?.username ?? "unknown",
     totalPairs: folder._count.pairs,
     favoriteCount: folder._count.favorites,
   }));
@@ -221,8 +221,8 @@ export async function repoSearchPublicFolders(
     visibility: folder.visibility,
     createdAt: folder.createdAt,
     userId: folder.userId,
-    userName: folder.user.name,
-    userUsername: folder.user.username,
+    userName: folder.user?.name ?? "Unknown",
+    userUsername: folder.user?.username ?? "unknown",
     totalPairs: folder._count.pairs,
     favoriteCount: folder._count.favorites,
   }));
@@ -300,8 +300,8 @@ export async function repoGetUserFavorites(input: RepoInputGetUserFavorites) {
     folderCreatedAt: fav.folder.createdAt,
     folderTotalPairs: fav.folder._count.pairs,
     folderOwnerId: fav.folder.userId,
-    folderOwnerName: fav.folder.user.name,
-    folderOwnerUsername: fav.folder.user.username,
+    folderOwnerName: fav.folder.user?.name ?? "Unknown",
+    folderOwnerUsername: fav.folder.user?.username ?? "unknown",
     favoritedAt: fav.createdAt,
   }));
 }