fix(projects): correct HTML lang attribute to standard format

pan0xc · honghuangdc · commit b520db3ef455 · 2026-02-10T22:44:37.000+08:00
diff --git a/index.html b/index.html
@@ -1,5 +1,5 @@
 <!doctype html>
-<html lang="zh-cmn-Hans">
+<html lang="zh-CN">
   <head>
     <meta charset="UTF-8" />
     <link rel="icon" href="/favicon.svg" />
