RibbonSpec constructor
Implementation
RibbonSpec({
required this.gradient,
this.baseY = 0.2, // normalized 0..1 of height
this.thickness = 1.0, // scales amplitude
this.speedFactor = 1.0, // local speed multiplier
this.elevation = 6.0, // dp (shadow + tint intensity)
this.opacity = 0.75, // translucency
});