Close nav dropdowns once the pointer leaves after a click

The panel opened on :focus-within, so the clicked link's focus kept it
pinned open after navigating. Open on keyboard focus only and release
focus on route change.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/components/site-header.tsx

@@ -19,6 +19,12 @@ export default function SiteHeader() {
     setOpen(false);
   }
 
+  // Drop focus left on a nav link after navigating so its dropdown doesn't stay pinned open.
+  useEffect(() => {
+    const el = document.activeElement;
+    if (el instanceof HTMLElement && el.closest(".site-header")) el.blur();
+  }, [pathname]);
+
   useEffect(() => {
     let lastY = window.scrollY;
     const onScroll = () => {