- web panel: screen recording now plays in the Details tab (large
  video card), removed from the Attachments thumbnails to avoid
  showing it twice
- screencast cap raised 1280 -> 2560 so wide viewports keep the
  cursor crop at native resolution (user viewport 2552 was scaled
  down to 1280, halving the video size)
- crop raised 512 -> 768 CSS px; GIF fallback stays at 512
- VP8 bitrate now scales with output size (~0.18 bits/px/frame,
  capped at 4 Mbps) instead of a fixed 1 Mbps
- e2e ffprobe assertion updated to the 768px cap

Co-Authored-By: Claude Code <noreply@anthropic.com>