fix: make role field optional in testimonial validation logic

src/app/dashboard/cms/page.tsx

@@ -479,7 +479,7 @@ export default function CmsPage() {
         if (!t.author?.trim()) return `Testimonial #${i + 1}: Author is required`;
         if (!t.content?.trim()) return `Testimonial #${i + 1}: Content is required`;
         if (!t.title?.trim()) return `Testimonial #${i + 1}: Title is required`;
-        if (!t.role?.trim()) return `Testimonial #${i + 1}: Role is required`;
+        // role is optional
       }
     }