feat: widget css file

public/locales/en/setting.json

@@ -287,6 +287,7 @@
     "default_value": "Default Value",
     "remark": "Remarks",
     "custom_style_tip": "if you want customize the widget position more precisely, use the widget element ID in your HTML or CSS file, like this",
+    "css_code_tip": "You can also customize CSS code, which will be loaded into the widget as a CSS file",
     "param_id": "Widget ID (server version>=v0.3.12)",
     "param_host": "Assign the user chatting with visitor(User ID)",
     "param_title": "chat popup title",

public/locales/zh/setting.json

@@ -287,6 +287,7 @@
     "default_value": "默认值",
     "remark": "备注",
     "custom_style_tip": "如果你想更精确控制挂件的样式，可以借助 widget 元素的 ID，自行写 CSS 样式，加到自己的 html 或者 css 文件中，如下所示：",
+    "css_code_tip": "也可以自定义 CSS 代码，会以 css 文件方式加载到挂件内",
     "param_id": "挂件 ID，可选设置 (服务器版本不低于 v0.3.12)",
     "param_host": "指定和谁聊天 (用户 ID)",
     "param_title": "聊天弹窗顶部标题",