support shareable search links via a ?q= URL parameter

frontend/app.js

@@ -9725,6 +9725,24 @@ async function registerServiceWorker() {
   }
 }
 
+// /?q=<query> — a shareable search link (same family as Share's /?v=&t=).
+// Runs after wireUI() so the search form's submit handler exists; the param
+// is stripped immediately so a reload doesn't re-run the search.
+function bootSearchFromUrl() {
+  let query = '';
+  try {
+    query = (new URLSearchParams(location.search).get('q') || '').trim();
+  } catch { return; }
+  if (!query) return;
+  try {
+    const u = new URL(location.href);
+    u.searchParams.delete('q');
+    history.replaceState(null, '', u.pathname + u.search + u.hash);
+  } catch { /* keep */ }
+  els.searchInput.value = query;
+  els.searchForm.requestSubmit();
+}
+
 // ============================================================================
 // Boot
 // ============================================================================
@@ -9785,6 +9803,7 @@ async function boot() {
   Presenter.boot();
   SectionRail.boot();
   Share.bootFromUrl();
+  bootSearchFromUrl();
   Party.boot();
   Remote.boot();
   Transition.renderButton();