fix: map chinese language requests to zh-CN

src/components/messageStream/hooks/usePostStream.ts

@@ -1,5 +1,6 @@
 import { useCallback, useEffect, useRef, useState } from "react";
 import { getJSON } from "../../../api";
+import { langQuery, type Lang } from "../../../i18n";
 import { MOCK_POSTS } from "../../../mocks/mockPosts";
 import type { Post, PostListResponse, PostScope } from "../../../types/post";
 
@@ -12,7 +13,7 @@ export type PostStreamParams = {
   scope: PostScope;
   type?: string;
   language?: string;
-  lang: string;
+  lang: Lang;
 };
 
 export type PostStreamResult = {
@@ -65,7 +66,7 @@ function filterMock(params: PostStreamParams): Post[] {
 
 function buildRealUrl(params: PostStreamParams, cursor?: string): string {
   const sp = new URLSearchParams();
-  sp.set("lang", params.lang);
+  sp.set("lang", langQuery(params.lang));
   sp.set("limit", String(PAGE_SIZE));
   if (params.scope.kind === "category") sp.set("category", params.scope.slug);
   if (params.type && params.type !== "all") sp.set("type", params.type);