Function render_all_frames 

pub fn render_all_frames<F>(
    backend: &dyn RasterizerBackend,
    config: &NativeRenderConfig,
    scene_fn: F,
) -> Result<Vec<PathBuf>, RasterError>
where
    F: FnMut(u32) -> Scene,

Render all frames sequentially to PNG files.

Each frame is rendered in order and saved as frame_000001.png, etc. Simple and debuggable, but slow for large frame counts.