perf: lighthouse optimizations - inline critical CSS, lazy-load routes, WebP images, fix CLS and contrast

js/app.js

@@ -30,7 +30,10 @@ async function initApp() {
 
     await import('./components/app-shell.js')
     
-    document.getElementById('app').innerHTML = '<app-shell></app-shell>'
+    const appEl = document.getElementById('app')
+    if (!appEl.querySelector('app-shell')) {
+        appEl.innerHTML = '<app-shell></app-shell>'
+    }
 
     if ('serviceWorker' in navigator) {
         try {