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/app/forms/form-elements/page.tsx

@@ -113,9 +113,9 @@ export default function FormElementsPage() {
             title="Checkbox and radio"
             className="space-y-5.5 !p-6.5"
           >
-            <Checkbox label="Checkbox Text" />
+            {/* <Checkbox label="Checkbox Text" />
             <Checkbox label="Checkbox Text" withIcon="check" />
-            <Checkbox label="Checkbox Text" withIcon="x" />
+            <Checkbox label="Checkbox Text" withIcon="x" /> */}
             <RadioInput label="Checkbox Text" />
             <RadioInput label="Checkbox Text" variant="circle" />
           </ShowcaseSection>