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.

rollup.config.js

@@ -34,24 +34,32 @@ function insertFrontmatter() {
   };
 }
 
-function build(filename, { src = SRC_DEFAULT, jekyll = false } = {}) {
+function build(
+  filename,
+  { src = SRC_DEFAULT, jekyll = false, outputName = null } = {}
+) {
+  const input = `${src}/${filename}.js`;
+
   return {
-    input: `${src}/${filename}.js`,
+    input,
     output: {
       file: `${DIST}/${filename}.min.js`,
       format: 'iife',
-      name: 'Chirpy',
+      ...(outputName !== null && { name: outputName }),
       banner,
       sourcemap: !isProd && !jekyll
     },
     watch: {
-      include: `${src}/**`
+      include: input
     },
     plugins: [
       babel({
         babelHelpers: 'bundled',
         presets: ['@babel/env'],
-        plugins: ['@babel/plugin-transform-class-properties']
+        plugins: [
+          '@babel/plugin-transform-class-properties',
+          '@babel/plugin-transform-private-methods'
+        ]
       }),
       nodeResolve(),
       isProd && terser(),
@@ -69,6 +77,7 @@ export default [
   build('page'),
   build('post'),
   build('misc'),
+  build('theme', { src: `${SRC_DEFAULT}/modules`, outputName: 'Theme' }),
   build('app', { src: SRC_PWA, jekyll: true }),
   build('sw', { src: SRC_PWA, jekyll: true })
 ];