[iOS, Android] Video is being truncated top and bottom on receiving desktop

### Steps to reproduce

1. Have one user dial-in via any mobile browser (Android, iOS and Safari, Chrome, Firefox, Brave tested)
2. Have one user dial-in via desktop

### Outcome

#### What did you expect?
See the full video from all participants

#### What happened instead?
The video from the mobile device is cut on top and bottom.

I guess this is happening because the transmitted image is vertical and not horizontal (as it is for desktops). I understand where this is coming from, but it's bad: For mobile users it's impossible to show your full face (also it looks right on your mobile device, it's just the receiver view which is truncated, so you have no clue what others are seeing).

Quick fix: Don't truncate and rather show black borders.

Ideal fix: Show all videos in a vertical frame rather than the horizontal frame. That means showing all videos like they come from mobile and truncate the desktop video (as people are higher than wider and on desktop the majority of the image you don't need to see).

### Operating system

iOS & Android

### Browser information

multiple browsers tested: Safari, Chrome, Firefox, Brave

### URL for webapp

_No response_

### Will you send logs?

No

No source files, tests, or entry points are identified in the issue. First reproduce the call with a mobile-browser participant and a desktop participant, then trace the receiving video layout and its aspect-ratio behavior. Done means the receiver can see the mobile participant's full video without unwanted top and bottom cropping.

Written by the indexing model from the issue text.