Replace rigid SCREEN_QUALITY_MAP (6 hardcoded VideoPreset strings) with a
builder function that computes bitrate, degradation preference, and content
hint from three independent axes (height, fps, content mode). Camera is
decoupled onto a fixed 720p30 preset so screen share changes no longer
affect camera quality. New ScreenShareSettingsPopover replaces the old
VideoQualityPopover with pill-style selectors. Store migrated to v5 with
backwards-compatible migration from videoQuality string.
Jannis Braun
f808a204e7