Function make_blur_texture_at 

fn make_blur_texture_at(
    device: &Device,
    config: &RenderConfig,
    width: u32,
    height: u32,
    label: &str,
) -> (Texture, TextureView)

Allocate a blur-stage texture at an explicit (width, height) — the downsampled pyramid wants each level smaller than the last, so the helper takes the dimensions directly rather than deriving them from config. Texture format follows config.texture_format so the blur output composes cleanly with render_texture / final_texture in the comp pass.