test(13-04): add tests for new backend form rendering

- Test gdrive: GdriveAuthToggle with OAuth Token and Service Account tabs
- Test dropbox: OAuthInstructions toggle button visible
- Test ftp: host, username, password, port, TLS mode fields
- Test webdav: URL, username, password, vendor select fields
- Test smb: host and username fields
- Test http: only URL field, no username/password

src/components/wizard/RemoteConfigStep.test.tsx

@@ -448,4 +448,59 @@ describe('RemoteConfigStep', () => {
       });
     });
   });
+
+  describe('New backend form rendering (Plan 13-04)', () => {
+    it('gdrive renders GdriveAuthToggle with OAuth Token and Service Account tabs', async () => {
+      renderWithBackend('gdrive');
+      await waitFor(() => {
+        expect(screen.getByText(/oauth token/i, { selector: 'button' })).toBeDefined();
+        expect(screen.getByText(/service account/i, { selector: 'button' })).toBeDefined();
+      });
+    });
+
+    it('dropbox renders OAuthInstructions toggle button', async () => {
+      renderWithBackend('dropbox');
+      await waitFor(() => {
+        expect(screen.getByRole('button', { name: /how to get your dropbox oauth token/i })).toBeDefined();
+      });
+    });
+
+    it('ftp renders host, username, password, port, TLS mode fields', async () => {
+      renderWithBackend('ftp');
+      await waitFor(() => {
+        expect(screen.getByLabelText(/host/i, { selector: 'input' })).toBeDefined();
+        expect(screen.getByLabelText(/username/i, { selector: 'input' })).toBeDefined();
+        expect(screen.getByLabelText(/^password/i, { selector: 'input' })).toBeDefined();
+        expect(screen.getByLabelText(/port/i, { selector: 'input' })).toBeDefined();
+        expect(screen.getByLabelText(/tls mode/i)).toBeDefined();
+      });
+    });
+
+    it('webdav renders URL, username, password, vendor select fields', async () => {
+      renderWithBackend('webdav');
+      await waitFor(() => {
+        expect(screen.getByLabelText(/webdav url/i, { selector: 'input' })).toBeDefined();
+        expect(screen.getByLabelText(/username/i, { selector: 'input' })).toBeDefined();
+        expect(screen.getByLabelText(/^password/i, { selector: 'input' })).toBeDefined();
+        expect(screen.getByLabelText(/vendor/i)).toBeDefined();
+      });
+    });
+
+    it('smb renders host and username fields', async () => {
+      renderWithBackend('smb');
+      await waitFor(() => {
+        expect(screen.getByLabelText(/host/i, { selector: 'input' })).toBeDefined();
+        expect(screen.getByLabelText(/username/i, { selector: 'input' })).toBeDefined();
+      });
+    });
+
+    it('http renders only URL field', async () => {
+      renderWithBackend('http');
+      await waitFor(() => {
+        expect(screen.getByLabelText(/^url/i, { selector: 'input' })).toBeDefined();
+      });
+      // No username or password fields for http (read-only)
+      expect(screen.queryByLabelText(/username/i, { selector: 'input' })).toBeNull();
+    });
+  });
 });