Function render_decoration_button 

pub fn render_decoration_button(
    buffer: &mut [u32],
    buf_w: u32,
    x: u32,
    y: u32,
    size: u32,
    button_type: DecorationButton,
    hovered: bool,
)

Render a single decoration button (close, maximize, or minimize).

Draws a small icon inside a square region starting at (x, y) with the given size. If hovered, the background is slightly highlighted.