add api for contact form
This pull request adds a contact form functionality to the web application. The changes include:
- Adding a new contact page with a form interface
- Implementing a contact API endpoint to handle form submissions
- Adding form validation for email and required fields
- Updating the navigation menu to include a contact link
- Removing some GitLab Duo specific content and streamlining the benefits list
The changes transform the application from an informational site about GitLab Duo integration to include interactive contact capabilities for users.