style: switch to LXGW Wenkai Screen

Noto Serif SC by default (400 weight) is still too light in 1080p 100% scale,
which may looks unclear sometimes.

docs/.vuepress/styles/palette.scss

@@ -1,3 +1,3 @@
 
 // force Noto Serif.
-$vp-font: '"Noto Serif SC", serif';
+$vp-font: '"LXGW WenKai Screen", sans-serif';

vuepress.config.ts

@@ -22,29 +22,15 @@ export default defineUserConfig({
   ],
 
   head: [
-    // 导入相应链接
-    ["link", { rel: "preconnect", href: "https://fonts.googleapis.com" }],
-    [
-      "link",
-      { rel: "preconnect", href: "https://fonts.gstatic.com", crossorigin: "" },
-    ],
     [
       "link",
       {
-        href: "https://fonts.googleapis.com/css2?family=Noto+Serif+SC:wght@400..700&display=swap",
-        as: "font",
-        crossorigin: "",
-      },
-    ],
-    [
-      "link",
-      {
-        href: "https://fonts.googleapis.com/css2?family=Noto+Serif+SC:wght@400..700&display=swap",
+        href: "https://cdn.jsdelivr.net/npm/lxgw-wenkai-screen-web/style.css",
         rel: "stylesheet",
-        as: "font",
-        crossorigin: "",
-        media: "print",
-        onload: "this.media='all'",
+        // as: "font",
+        // crossorigin: "",
+        // media: "print",
+        // onload: "this.media='all'",
       },
     ],
   ],