mobile server_page text theme & fix lang.py and update langs

src/lang/cn.rs

@@ -327,6 +327,9 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("Account", "账户"),
         ("Theme", "主题"),
         ("Dark Theme", "暗黑主题"),
+        ("Dark", "黑暗"),
+        ("Light", "明亮"),
+        ("Follow System", "跟随系统"),
         ("Enable hardware codec", "使用硬件编解码"),
         ("Unlock Security Settings", "解锁安全设置"),
         ("Enable Audio", "允许传输音频"),