chore: release v5.5.3

- Bump version from 5.5.3-b2 to 5.5.3 in package.json
- Update third-party dependencies:
  * algolia_search: 5.43.0 -> 5.46.0
  * docsearch: 4.3.1 -> 4.3.2
  * fancybox: 6.1.4 -> 6.1.7
  * katex: 0.16.25 -> 0.16.27
  * mermaid: 11.12.1 -> 11.12.2
  * waline: 3.7.1 -> 3.8.0

perf: optimize JavaScript performance
- Add defer attribute to script tags in pjax and prismjs
- Improve DOM content loading timing in pjax
- Optimize utilities with better throttle implementation
- Cache header positions for TOC performance
- Optimize related posts generation with Maps
- Improve archive helpers performance

fix: improve error handling and UI fixes
- Replace process.exit with proper error throwing
- Fix tooltip positioning with boundary checks
- Add btn-effects to readmode exit button
- Fix element height calculation for hidden elements
- Improve image filters in dark mode (brightness .88, contrast .95)

style: code improvements and consistency
- Refactor random cover generation with generator pattern
- Optimize data processing in helpers
- Clean up unused functions and improve code structure
- Fix Chinese translation: 页 -> 頁

layout/includes/third-party/pjax.pug

@@ -14,9 +14,9 @@ if choose
     else
       - pjaxSelectors.unshift('meta[name="description"]')
 
-script(src=url_for(theme.asset.pjax))
+script(src=url_for(theme.asset.pjax) defer)
 script.
-  (() => {
+  document.addEventListener('DOMContentLoaded', () => {
     const pjaxSelectors = !{JSON.stringify(pjaxSelectors)}
 
     window.pjax = new Pjax({
@@ -65,10 +65,9 @@ script.
 
     document.addEventListener('pjax:error', e => {
       if (e.request.status === 404) {
-        const usePjax = !{theme.pjax && theme.pjax.enable}
         !{theme.error_404 && theme.error_404.enable}
-          ? (usePjax ? pjax.loadUrl('!{url_for("/404.html")}') : window.location.href = '!{url_for("/404.html")}')
+          ? pjax.loadUrl('!{url_for("/404.html")}')
           : window.location.href = e.request.responseURL
       }
     })
-  })()
+  })