FE011: Improve Contact Us page using reusable ContactForm

[Deepanshugarg11]

Summary

This PR updates the Contact Us page by reusing the existing reusable ContactForm component that has already been merged into main, following the team lead's feedback.

Changes Made

• Reused the shared ContactForm component instead of maintaining a duplicate implementation.
• Updated the Contact Us page to use the reusable component.
• Preserved the existing page layout, contact information cards, and styling.
• Added loading state with a disabled submit button and loading spinner.
• Added success and error feedback for the mocked submission flow.
• Improved validation, accessibility, and responsive behaviour.
• Updated the reusable component to support the required Contact Us functionality.
• Confirmed that there is currently no backend Contact Us API, so the form continues to use a frontend mock submission with a clear preview message.

Testing

Manual Testing

• Verified Contact Us page renders correctly.
• Verified required field validation.
• Verified email validation.
• Verified loading state and spinner.
• Verified success message after submission.
• Verified error message.
• Verified responsive layout.

Automated Testing

• Updated ContactForm unit tests.
• All tests pass successfully.

Notes

No backend Contact Us endpoint currently exists, so the form intentionally uses mocked frontend submission behaviour until backend integration is available.