Increase search debounce to 500ms and add Enter to search

Reduce unnecessary API calls while typing by increasing the debounce
delay. Allow pressing Enter to trigger an immediate search when no
result is selected.

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

Author: twaugh

src/ui.ts

@@ -54,7 +54,7 @@ export function createSearchModal(): void {
   const debouncedSearch = debounce(async (...args: unknown[]) => {
     const query = args[0] as string;
     await performSearch(query);
-  }, 300);
+  }, 500);
 
   input.addEventListener("input", () => {
     historyIndex = -1;
@@ -167,6 +167,10 @@ function handleKeydown(e: KeyboardEvent): void {
     (active as HTMLElement).dispatchEvent(
       new MouseEvent("click", { shiftKey: e.shiftKey, bubbles: true }),
     );
+  } else if (e.key === "Enter" && !active && input && document.activeElement === input) {
+    e.preventDefault();
+    const query = input.value.trim();
+    if (query) performSearch(query);
   } else if (e.key === "c" && (e.ctrlKey || e.metaKey) && active) {
     e.preventDefault();
     const blockId = active.getAttribute("data-block-id");