Function ui_textarea 

pub fn ui_textarea(
    id: u32,
    x: f32,
    y: f32,
    w: f32,
    h: f32,
    placeholder: &str,
) -> String

Render a multi-line text input. Returns the current text content.

Supports cursor navigation (←/→/↑/↓/Home/End), selection (Shift+arrows), copy/cut/paste, select-all, scrolling, and Enter to insert a newline. Use ui_textarea_with_value to seed an initial value.