Add demo config for StackBlitz

demo/src/App.svelte

@@ -53,9 +53,8 @@
     // 判断 mode 后三个字符是否是 _en
     // Determine whether the last three characters of mode are _en
     const englishMode = mode.slice(-3) === '_en';
-    const devMode = mode === 'development';
     onMount(() => {
-        if (!devMode) {
+        if (mode != 'production' && mode != 'development' && mode != 'english') {
             // 英文模式去掉 mode 后面的 _en 作为 nav
             // English mode removes _en after mode as nav
             const nav = englishMode ? mode.slice(0, -3) : mode;