Implement local storage management for selected chain and task in MainPage component. Add state restoration logic on component mount and ensure cleanup on task completion. This enhances user experience by preserving selections across sessions.

src/context/ChallengeContext.tsx

@@ -177,6 +177,8 @@ export const ChallengeProvider = ({ children }: PropsWithChildren) => {
     if (isBrowser()) {
       window.localStorage.removeItem(USER_ID_KEY)
       window.localStorage.removeItem(USER_NICKNAME_KEY)
+      window.localStorage.removeItem('challengeSelectedChainId')
+      window.localStorage.removeItem('challengeSelectedTaskId')
     }
   }, [])