SSR support

[Mister-Hope]

It would be great for artalk to support SSR (or SSG in another way).

To support this, artalk must not access any dom realted variables before actual api call (i.e.: Artalk.init)

Currently artalk is at least accessing window object in main context.

Solution

before:

// ...
window.localstorage
// ...

export default class Aralk {
  // ..
}

after:

// ...

const getLocalConfig = () => {
 // ...
  window.localstorage
 // ...

 return xxx;
}

// ...

export default class Aralk {
  // ..
  init() {
   const config = getLocalConfig()
  }
  // ...
}

ReferenceError: window is not defined
    at new <anonymous> (/home/mister-hope/projects/vuepress/vuepress-theme-hope/node_modules/.pnpm/artalk@2.7.1/node_modules/artalk/dist/Artalk.js:1:10052)
    at /home/mister-hope/projects/vuepress/vuepress-theme-hope/node_modules/.pnpm/artalk@2.7.1/node_modules/artalk/dist/Artalk.js:1:9941
    at /home/mister-hope/projects/vuepress/vuepress-theme-hope/node_modules/.pnpm/artalk@2.7.1/node_modules/artalk/dist/Artalk.js:1:1281
    at Object.<anonymous> (/home/mister-hope/projects/vuepress/vuepress-theme-hope/node_modules/.pnpm/artalk@2.7.1/node_modules/artalk/dist/Artalk.js:1:1419)
    at Module._compile (node:internal/modules/cjs/loader:1376:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1435:10)
    at Module.load (node:internal/modules/cjs/loader:1207:32)
    at Module._load (node:internal/modules/cjs/loader:1023:12)
    at cjsLoader (node:internal/modules/esm/translators:345:17)
    at ModuleWrap.<anonymous> (node:internal/modules/esm/translators:294:7)
 ELIFECYCLE  Command failed with exit code 1.

[qwqcode]

感谢反馈，这个问题是我以前没有考虑到的，现在正在进行持续改进！

[Mister-Hope]

我晚点提一个pr修复它

[qwqcode]

我已经找出所有顶层的 const xxx = window.xxx 了，刚刚测试跑 SSG 编译，似乎能通过！🤣 这个问题似乎已经修复了

[qwqcode]

我再测测，非常感谢！

[qwqcode]

目前这个测试用例已经通过编译，之前会报 window undefined 的错误：

https://github.com/ArtalkJS/Artalk/blob/master/test/ssg-test/.vitepress/theme/Artalk.vue

该用例中包含：

• 在 SSG 编译时 import Artalk from 'artalk' 引入而不是 import('artalk') 动态引入
• 在 onMounted 外调用 Artalk.use (非 Artalk.init 的方法，没有引用 window) 不报错
• 在 onMounted 和 onUnmounted 以及 watch 调用 Artalk.init, Artalk.update 和 Artalk.destroy 不报错

相关参考文档：

• https://vitepress.dev/guide/ssr-compat#ssr-compatibility
• https://vuejs.org/guide/scaling-up/ssr.html

fixes #608