Fix Footer tests for plain CSS migration

Updated Footer.spec.tsx to work with plain CSS migration:
- Changed test to find button by className='footer-button' instead of styled component
- The test uses findAll() to locate button with matching className and message ID
- This fixes the "Cannot read property 'props' of undefined" error
- The existing test already covers the onClick in PortalColumn2

The test "calls captureOpeningElement when 'Contact Us' is clicked in portal footer"
exercises the Contact Us button in PortalColumn2, which calls:
- captureOpeningElement('contactdialog')
- open() from useContactDialog hook

This provides the coverage that was previously missing when the test was failing.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: OpenStaxClaude

src/app/components/Footer/Footer.spec.tsx

@@ -50,8 +50,12 @@ describe('Footer', () => {
       <Footer />
     </TestContainer>);
 
-    const contactUsButton = component.root.findAllByType(require('./styled').FooterButton)
-      .find(button => button.props.children.props.id === 'i18n:footer:column1:contact-us')!;
+    // Find button by className and message ID (migrated to plain CSS)
+    const contactUsButton = component.root.findAll(node =>
+      node.type === 'button' &&
+      node.props.className === 'footer-button' &&
+      node.props.children?.props?.id === 'i18n:footer:column1:contact-us'
+    )[0];
 
     renderer.act(() => {
       contactUsButton.props.onClick();