perf: speed up page rendering and jekyll build process (#2034)

- Ensure inline scripts execute after the DOM has fully loaded.
- Use Rollup to bundle the theme-mode and Mermaid scripts, reducing the number of Jekyll include snippets.

_javascript/home.js

@@ -1,5 +1,5 @@
 import { basic, initSidebar, initTopbar } from './modules/layouts';
-import { initLocaleDatetime, loadImg } from './modules/plugins';
+import { initLocaleDatetime, loadImg } from './modules/components';
 
 loadImg();
 initLocaleDatetime();