refactor(core): optimize image loading

- JavaScript runs so fast that LQIP will never be detected
- Increase the running priority of image processing in posts

Enhancement for #1267

_javascript/post.js

@@ -7,7 +7,6 @@ import {
   toc
 } from './modules/plugins';
 
-basic();
 initSidebar();
 initTopbar();
 loadImg();
@@ -15,3 +14,4 @@ imgPopup();
 initLocaleDatetime();
 initClipboard();
 toc();
+basic();