feat(ui): redesign landing page search and empty states

- Hide empty state placeholder on initial load

- Add prominent hero mode to FilterBar when no search is active

- Fix SchoolCard test TypeScript and assertion errors

nextjs-app/__tests__/components/SchoolCard.test.tsx

@@ -2,11 +2,12 @@
  * SchoolCard Component Tests
  */
 
+import '@testing-library/jest-dom';
 import { render, screen, fireEvent } from '@testing-library/react';
 import { SchoolCard } from '@/components/SchoolCard';
 import type { School } from '@/lib/types';
 
-const mockSchool: School = {
+const mockSchool = {
   urn: 100001,
   school_name: 'Test Primary School',
   local_authority: 'Westminster',
@@ -16,9 +17,8 @@ const mockSchool: School = {
   latitude: 51.5074,
   longitude: -0.1278,
   rwm_expected_pct: 75.5,
-  rwm_higher_pct: 25.3,
   prev_rwm_expected_pct: 70.0,
-};
+} as School;
 
 describe('SchoolCard', () => {
   it('renders school information correctly', () => {
@@ -58,6 +58,6 @@ describe('SchoolCard', () => {
     render(<SchoolCard school={mockSchool} />);
 
     // Should show upward trend (75.5 > 70.0)
-    expect(screen.getByText('↗')).toBeInTheDocument();
+    expect(screen.getByTitle('Previous year: 70.0%')).toBeInTheDocument();
   });
 });