test(13-03): add search filter and category collapse tests

- 6 new test cases covering REMOTE-03 acceptance criteria
- Tests: all 3 category headings render, ftp search shows FTP+SFTP
- Tests: no-match query hides all categories
- Tests: Cloudflare description match finds S3-Compatible
- Tests: all 18 backend cards render without search
- Tests: category heading hidden when all backends filtered out

src/components/wizard/BackendSelectionStep.test.tsx

@@ -2,8 +2,9 @@
 // Covers WIZD-01: card grid renders Azure Blob, Amazon S3, S3-Compatible (Azure first)
 // Covers WIZD-04: remote name field validates alphanumeric/dash/underscore
 // Covers POLISH-04: auto-scroll to first errored field on validation failure
+// Covers REMOTE-03: category-grouped, searchable backend selection with icons
 import { describe, it, expect, beforeEach, vi } from 'vitest';
-import { render, screen, waitFor } from '@testing-library/react';
+import { render, screen, waitFor, fireEvent } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
 import { WizardProvider } from '../../store/context';
 import { BackendSelectionStep } from './BackendSelectionStep';
@@ -159,4 +160,60 @@ describe('BackendSelectionStep', () => {
       });
     });
   });
+
+  describe('REMOTE-03: category grouping and search', () => {
+    it('renders all three category headings when no search query', () => {
+      renderStep();
+      expect(screen.getByText('Cloud Object Storage')).toBeDefined();
+      expect(screen.getByText('Cloud Drives')).toBeDefined();
+      expect(screen.getByText('Protocol-based')).toBeDefined();
+    });
+
+    it('typing "ftp" shows FTP and SFTP backends', () => {
+      renderStep();
+      const searchInput = screen.getByPlaceholderText('Search backends...');
+      fireEvent.change(searchInput, { target: { value: 'ftp' } });
+      expect(screen.getByText('FTP')).toBeDefined();
+      expect(screen.getByText('SFTP')).toBeDefined();
+      // Unrelated cloud backends should not be visible
+      expect(screen.queryByText('Amazon S3')).toBeNull();
+      expect(screen.queryByText('Google Drive')).toBeNull();
+    });
+
+    it('typing a query with no matches hides all category headings', () => {
+      renderStep();
+      const searchInput = screen.getByPlaceholderText('Search backends...');
+      fireEvent.change(searchInput, { target: { value: 'zzznomatch999' } });
+      expect(screen.queryByText('Cloud Object Storage')).toBeNull();
+      expect(screen.queryByText('Cloud Drives')).toBeNull();
+      expect(screen.queryByText('Protocol-based')).toBeNull();
+    });
+
+    it('searching "Cloudflare" finds S3-Compatible via description match', () => {
+      renderStep();
+      const searchInput = screen.getByPlaceholderText('Search backends...');
+      fireEvent.change(searchInput, { target: { value: 'Cloudflare' } });
+      expect(screen.getByText('S3-Compatible')).toBeDefined();
+    });
+
+    it('renders all 18 backend cards when no search active', () => {
+      renderStep();
+      // Count all backend card buttons (exclude Next button)
+      const backendContainer = screen.getByTestId('backend-cards');
+      const cardButtons = backendContainer.querySelectorAll('button');
+      expect(cardButtons.length).toBe(18);
+    });
+
+    it('hides category heading when all its backends are filtered out', () => {
+      renderStep();
+      const searchInput = screen.getByPlaceholderText('Search backends...');
+      // "ftp" matches only Protocol-based backends (FTP, SFTP)
+      fireEvent.change(searchInput, { target: { value: 'ftp' } });
+      // Cloud Object Storage and Cloud Drives should not appear
+      expect(screen.queryByText('Cloud Object Storage')).toBeNull();
+      expect(screen.queryByText('Cloud Drives')).toBeNull();
+      // Protocol-based should still appear
+      expect(screen.getByText('Protocol-based')).toBeDefined();
+    });
+  });
 });