feat: add auto-exit on empty list and improve bindings

[LangLangBart]

Description

When pressing ⌃ Control + T or ⏎ Enter, the notification is automatically marked as read. When the list is empty, the program exits automatically after a reload.

In the GIF below, the old behavior reloads the list with a message while fzf remains active. The new behavior will exit fzf if the list becomes empty after pressing Ctrl + T.

Pro

• Fewer hotkey presses
• Viewing notifications would mimic the behavior of the GitHub web interface by automatically marking notifications as read

Negative

• Requires fzf 0.45.0, but many package repositories still ship quite outdated fzf versions^1
  • Because of that reason is is just a draft