As a student, I want to participate in a study hour challenge initiated by another user. Sprint 2.

[ ] Notify the user when they receive a challenge from another user.
[ ] Display the challenge details, including duration and challenger's ID, in an inbox or notification center.
[ ] Allow the user to accept or reject the challenge from the inbox or notification center.
[ ] If the challenge is accepted, display the ongoing competition with a display to show user ID and what type of challenge.
[x] Update the study hour statistics in real-time during the challenge period.
[x] Notify both users of the challenge outcome at the end of the competition period.

Asyaakkusss / hungry-cat-main