Feature Request: Custom Toast Message for Invalid Username

[imsachin49]

Description

Add a custom toast message when a user searches for an incorrect or non-participant LeetCode username for a contest.

• We can show text "Rating for xyz not available for this contest."

• It will just Improve the user experience.

• A simple toast Error like this will work!

[baoliay2008]

@imsachin49 Thanks for your suggestion, sounds good to me.

One thing to mention is we should use the DaisyUI component here, which is consistent with the project.