feat: artalk 支持點擊打開大圖

feat: 設置了隨系統而切換淺色和深色模式後，評論和 mermaind 也會跟隨切換顏色
feat: artalk 最新評論，從 artalk 配置讀取頭像 CDN 和默認頭像
fix: 修復代碼塊在未展開時，點擊複製按鈕，無法複製的 bug
improvement: 代碼和性能優化
improvement: artalk 獲取評論數，由 LoadCountWidget 改為 loadCountWidget

layout/includes/third-party/comments/disqus.pug

@@ -2,19 +2,21 @@
 
 script.
   function loadDisqus () {
-    var disqus_config = function () {
+    const disqus_config = function () {
       this.page.url = '!{ page.permalink }'
       this.page.identifier = '!{ url_for(page.path) }'
       this.page.title = '!{ disqusPageTitle }'
-    };
+    }
 
-    window.disqusReset = () => {
+    const disqusReset = () => {
       DISQUS.reset({
         reload: true,
         config: disqus_config
       })
     }
 
+    btf.addModeChange('disqus', disqusReset)
+
     if (window.DISQUS) disqusReset()
     else {
       (function() { 
@@ -24,10 +26,6 @@ script.
         (d.head || d.body).appendChild(s);
       })();
     }
-
-    document.getElementById('darkmode').addEventListener('click', () => {
-      setTimeout(() => window.disqusReset(), 200)
-    })
   }
 
   if ('!{theme.comments.use[0]}' === 'Disqus' || !!{theme.comments.lazyload}) {