Function draw_floating_damage 

pub fn draw_floating_damage(
    ui: &mut UiLayer,
    x: f32,
    y: f32,
    damage: i32,
    age: f32,
    is_crit: bool,
)

Draw a damage number floating up from a position.

age is 0.0 to 1.0 (lifetime progress). The number fades and rises.