fn wallpaper_rgba(name: &str, width: u32, height: u32) -> Vec<u8> ⓘExpand description
Generate a procedural wallpaper backdrop as packed RGBA8 (width*height*4).
A soft diagonal three-stop gradient with a faint aurora band, keyed on
name’s palette. License-clean (no bundled asset), deterministic, and pure
— exhaustively testable. (ISS-15.)