feat(marketing): add contacts section and improve checkbox UI

This commit introduces a new "Contacts" section to the marketing page, which is now the fifth step in the page's flow.

Additionally, the Checkbox component has been enhanced with a smooth transition effect on state change. This provides better visual feedback and a more polished user experience.

src/components/FormElements/checkbox.tsx

@@ -43,7 +43,7 @@ export function Checkbox({
 
           <div
             className={cn(
-              "mr-2 flex size-5 items-center justify-center rounded border border-dark-5 peer-checked:border-primary dark:border-dark-6 peer-checked:[&>*]:block",
+              "mr-2 flex size-5 items-center justify-center rounded border border-dark-5 peer-checked:border-primary dark:border-dark-6 peer-checked:[&>*]:block transition-all duration-300",
               withBg
                 ? "peer-checked:bg-primary [&>*]:text-white"
                 : "peer-checked:bg-gray-2 dark:peer-checked:bg-transparent",