258ad3511d
Pass width/height as { ideal: N } constraints (not exact values) so
Chromium preserves the source's aspect ratio instead of cropping
non-matching monitors. Previously a 1920x1200 monitor under a 1080p
preset lost the bottom 120px including the Windows taskbar.
The auto-preset fallback now omits width/height entirely (both set to
undefined) so getDisplayMedia uses the screen's native resolution.
Cast through `unknown` to satisfy LiveKit's VideoResolution type, which
declares width/height as plain number but Chromium accepts the full
MediaTrackConstraints shape at runtime.