agent: foundation — sync incremental changes from legacy codebase

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/lib/pages/HistoryPage.svelte

@@ -35,6 +35,7 @@
   );
 
   function clearAll() {
+    if (!confirm("Delete all history? This can't be undone.")) return;
     history.splice(0);
     saveHistory();
     expandedId = null;