perf: move custom-app js to load only on homepage

custom-app/src/main.tsx

@@ -34,7 +34,8 @@
   document.getElementById('builtwithfern')?.remove()
 }
 
-window.addEventListener('load', async () => {
+const initializeApp = async () => {
+  console.log('initializeApp')
   // Only render on /docs or /docs/
   const initialPath = window.location.pathname.replace(/\/+$/, '')
 
@@ -67,4 +68,14 @@
   })
 
   observer.observe(document.body, { childList: true, subtree: true })
+}
+
+// Run immediately when script loads (for direct navigation to homepage)
+console.log('running initializeApp')
+initializeApp()
+
+// Also run on popstate (for back/forward navigation)
+window.addEventListener('popstate', () => {
+  console.log('popstate')
+  initializeApp()
 })