Added unread message count badge on the Jump to bottom button (#131)

[alanpoon]

https://github.com/user-attachments/assets/1b0ad9d2-9da6-4da4-80b7-3b1965c708d0

• [ x ] Scroll to the most recent message
• [ ] Jump to the first unread message

Solution to solve this issue JTB

Logic added:

1. whenever there is new timeline item, check for number of unread message and draw accordingly onto the unread_notification_badge.
2. Whenever sending fully read receipt, clear the content unread_notification_badge.