style(font): 移除默认代码字体，改为 Cascadia Mono

2. del: 删除 setting-utils.ts 中的 AUTO_MODE

package.json

@@ -24,8 +24,6 @@
     "@expressive-code/core": "^0.41.3",
     "@expressive-code/plugin-collapsible-sections": "^0.41.3",
     "@expressive-code/plugin-line-numbers": "^0.41.3",
-    "@fontsource-variable/jetbrains-mono": "^5.2.6",
-    "@fontsource/roboto": "^5.2.6",
     "@iconify-json/fa6-brands": "^1.2.6",
     "@iconify-json/fa6-regular": "^1.2.4",
     "@iconify-json/fa6-solid": "^1.2.4",