Improve unread message navigation, auto-scroll behavior, and download experience on desktop

[chinariicii]

Is your feature request related to a problem?

yes

Describe the solution you'd like

1. Currently, sidebar folders only show the number of unread messages. When a folder contains many groups and contacts, users must scroll through the list for a long time to locate the actual unread messages, which is inefficient.
2. When opening a chat with unread messages, the window stays at the previously read position. Users must manually scroll down to the “new messages (unread messages)” area before the unread indicator disappears, which is not intuitive.
3. On the desktop version, file and image downloads are often extremely slow or fail to complete, negatively affecting daily usage.

Describe alternatives you've considered

1. Add a quick unread-message navigation feature for sidebar folders:
   • Double-clicking a folder jumps to the first unread message;
   • Each subsequent double-click jumps to the next unread message in sequence.
   This would significantly reduce manual scrolling and improve efficiency.
2. When opening a chat with unread messages:
   • Automatically scroll to the bottom by default, showing the latest messages and marking the chat as read;
   • Optionally provide an “up arrow” button that allows users to return to their previous reading position if needed.
3. Add a “download acceleration” feature or otherwise optimize the desktop download mechanism to improve download speed and reliability for files and images.

Additional context

Similar features are already available in many non-Telegram messaging applications and have proven to be effective in improving message handling efficiency and overall user experience.