Backend TUI Tutorial

let draw_list = @frontend.build_draw_list(scene, render_view)
let config = @tui.TuiRenderConfig::default()
let frame = @tui.render_frame(draw_list, config)
println(frame)

Use TuiRenderConfig::sized(width, height) when dimensions come from the current terminal.

To change the background:

let config = { @tui.TuiRenderConfig::default(), background_pattern: @tui.blank_background }

terminal_y_scale belongs to this backend because it compensates for terminal cell shape rather than geometry or camera math.