Function build_to_disk 

pub fn build_to_disk(
    options: BuildOptions,
    out_dir: &Path,
) -> Result<BuildStats, WebUIError>

Build a WebUI application and write output files to disk.

Writes protocol.bin, any external CSS files, and static component assets to out_dir. Creates out_dir if it does not exist.

Errors

Returns WebUIError on build failure or if output files cannot be written.