Fix search input losing focus on mouse click

The click-outside handler was checking for .subhead (a BEM class removed
in the Tailwind refactor) so every click including on the input itself
triggered closeSearch(). Now checks for the actual search label and popup.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

static/js/app.js

@@ -187,7 +187,12 @@
   }
 
   document.addEventListener('click', e => {
-    if (searchPop && searchPop.dataset.open === 'true' && !e.target.closest('.subhead')) closeSearch();
+    if (searchPop && searchPop.dataset.open === 'true') {
+      const inSearch = e.target.closest('label[for="searchInput"]')
+                    || e.target.id === 'searchInput'
+                    || e.target.closest('#searchpop');
+      if (!inSearch) closeSearch();
+    }
   });
 
   function closeSearch() {