Shrink header by removing gaps on small screens.

src/components/HeaderControls.vue

@@ -211,6 +211,9 @@ onBeforeUnmount(() => {
   gap: 1rem;
 }
 
+@media (max-width: 600px) {
+  .header-controls { gap: 0.1rem; }
+}
 /* Group search + spacer so outer gap doesn't create unwanted space */
 .search-with-spacer {
   display: flex;