Function write_read_save_file 

pub fn write_read_save_file(
    project_dir: &Path,
    scene_rows: &[(String, Vec<u8>)],
) -> Result<()>

Write the original per-scene read-flag file (savedata/read.sav).

C++ stores every scene row by scene name, followed by the exact byte count and one byte per read flag. Keeping the scene name is important because scene indices can move when scripts are rebuilt.