Refactor ChallengesSection component to utilize initial challenges and users data: Replace fetching logic with props for challenges and users, streamline challenge creation with a dedicated form component, and enhance UI for better user experience.

components/ui/index.ts

@@ -2,6 +2,7 @@ export { default as Avatar } from "./Avatar";
 export { default as Button } from "./Button";
 export { default as Input } from "./Input";
 export { default as Textarea } from "./Textarea";
+export { default as Select } from "./Select";
 export { default as Card } from "./Card";
 export { default as Modal } from "./Modal";
 export { default as Badge } from "./Badge";