fix(typeahead): close() cancels the pending debounce

An abandoned query no longer fires a stale fetch after the dropdown
closed, and loading can't stay stuck on true. Test pins both.

Review round 3: Felix suggestion.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/lib/shared/hooks/useTypeahead.svelte.test.ts

@@ -117,6 +117,17 @@ describe('createTypeahead', () => {
 		expect(ta.loading).toBe(false);
 	});
 
+	it('close() cancels the pending debounce — no stale fetch fires, loading resets', async () => {
+		const fetchUrl = vi.fn().mockResolvedValue([{ id: '1' }]);
+		const ta = createTypeahead({ fetchUrl, debounceMs: 300 });
+		ta.setQuery('foo');
+		expect(ta.loading).toBe(true);
+		ta.close();
+		expect(ta.loading).toBe(false);
+		await vi.advanceTimersByTimeAsync(300);
+		expect(fetchUrl).not.toHaveBeenCalled();
+	});
+
 	it('setActiveIndex updates activeIndex', () => {
 		const ta = createTypeahead({ fetchUrl: vi.fn().mockResolvedValue([]) });
 		expect(ta.activeIndex).toBe(-1);

frontend/src/lib/shared/hooks/useTypeahead.svelte.ts

@@ -40,6 +40,10 @@ export function createTypeahead<T>(options: Options<T>) {
 	function close() {
 		isOpen = false;
 		activeIndex = -1;
+		// Cancel the pending debounce — an abandoned query must not fire a stale
+		// fetch after the dropdown closed, nor leave loading stuck on true.
+		clearTimeout(debounceTimer);
+		loading = false;
 	}
 
 	function setActiveIndex(idx: number) {