feat(search): show spinner in search input while navigation is in-flight

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

frontend/src/routes/page.svelte.spec.ts

@@ -240,6 +240,16 @@ describe('Home page – error state', () => {
 	});
 });
 
+// ─── Loading spinner ──────────────────────────────────────────────────────────
+
+describe('Home page – loading spinner', () => {
+	it('does not show spinner by default', async () => {
+		render(Page, { data: emptyData });
+		const spinner = page.getByRole('status');
+		await expect.element(spinner).not.toBeInTheDocument();
+	});
+});
+
 // ─── Sort controls ────────────────────────────────────────────────────────────
 
 describe('Home page – sort controls', () => {