[FR] Number of unread articles on reading modal

[PhilJbt]

Is your feature request related to a problem? Please describe.
I'm following a lot of sources, and I often need to know how many articles I have left to read without having to close the article currently displayed.

Describe the solution you'd like
The reading modal should display the number of articles left to read. (1)

Describe alternatives you've considered
A progress bar at the top of the main window representing the percentage of articles left to read might be sufficient. (2)

Additional context
(1)

(2)