isDark method
Determines whether the given color is "dark".
A color is considered dark if its brightness is less than 128. The brightness is calculated based on the RGB values of the color.
Example:
Color darkColor = Color(0xFF1A1A1A);
print(darkColor.isDark()); // Output: true
Color lightColor = Color(0xFFFFF1F1);
print(lightColor.isDark()); // Output: false
Implementation
bool isDark() => getBrightness() < 128.0;