Adapt web-client to updates in PeerTube 7.3

[mykhailodanilenko]

1. Enable playlist sorting by priority (videoChannelPosition)
2. Enable scheduled live streams

[mykhailodanilenko]

Add feature toggle for the sorting based on if instance supports it (updated to >7.3), call /config endpoint on instance change to be able to determine

[ar9708]

When copying the debug info for a site, I would like us to have additional fields.

Existing:

{
  "buildInfo": { "BUILD_TIMESTAMP": "2025-09-22T10:25:23Z" },
  "OS": "Mac OS version 10.15.7",
  "dimensions": "1470 x 956",
  "device": "Apple Macintosh",
  "orientation": "landscape",
  "deviceType": "DESKTOP",
  "browser": "Chrome 140.0.0.0",
  "playerImplementation": "video.js"
}

New things I'd like to have added:

{
  // ...
  "backend": {
    "hostname": "tube.rebellion.global",
    "version": "7.2"
  }
}