Introduced a new footer in `MainLayout.razor` with copyright
information, a link to "Digital Data GmbH," and a privacy
policy link. Added two new privacy policy files
(`privacy-policy.en-US.html` and `privacy-policy.fr-FR.html`)
to the project and configured them to always copy to the
output directory.
Updated `app.css` to adjust layout heights to accommodate
the footer. Added new styles for the footer, including a
gradient background, responsive design, and hover effects
for links.