themeFromOscColor function
Parse an OSC color response data string into a theme.
Implementation
SystemTheme? themeFromOscColor(String data) {
final rgb = _parseOscRgb(data);
if (rgb == null) return null;
// ITU-R BT.709 relative luminance
final luminance = 0.2126 * rgb.r + 0.7152 * rgb.g + 0.0722 * rgb.b;
return luminance > 0.5 ? SystemTheme.light : SystemTheme.dark;
}