fix: auto-expand deep-linked DeepDive/Example after hydration

Reading window.location.hash during render returned false under the App
Router (the server render sees no hash), so the queued-expand ref stuck at
false and deep-linked DeepDive/Example blocks no longer opened on load.
Move the hash check into the post-mount effect so the initial render stays
deterministic and the deep link expands again after hydration.

Author: aurorascharff

src/components/MDX/ExpandableExample.tsx

@@ -16,7 +16,7 @@ import {IconDeepDive} from '../Icon/IconDeepDive';
 import {IconCodeBlock} from '../Icon/IconCodeBlock';
 import {Button} from '../Button';
 import {H4} from './Heading';
-import {useEffect, useRef, useState} from 'react';
+import {useEffect, useState} from 'react';
 
 interface ExpandableExampleProps {
   children: React.ReactNode;
@@ -34,17 +34,16 @@ function ExpandableExample({children, excerpt, type}: ExpandableExampleProps) {
   const isExample = type === 'Example';
   const id = children[0].props.id;
 
-  const shouldAutoExpand =
-    typeof window !== 'undefined' && id === window.location.hash.slice(1);
-  const queuedExpandRef = useRef<boolean>(shouldAutoExpand);
   const [isExpanded, setIsExpanded] = useState(false);
 
+  // Auto-expand when deep-linked to this section. Read the hash in an effect
+  // (not during render) so the initial render stays deterministic across the
+  // server and client hydration.
   useEffect(() => {
-    if (queuedExpandRef.current) {
-      queuedExpandRef.current = false;
+    if (id === window.location.hash.slice(1)) {
       setIsExpanded(true);
     }
-  }, []);
+  }, [id]);
 
   return (
     <details