Function download_java_with_progress 

pub async fn download_java_with_progress(
    version: u32,
    base_dir: &Path,
    progress: ProgressFn,
) -> Result<PathBuf>

Reuse an extracted JRE or download one, reporting progress through the callback. During Downloading Java, counts are downloaded and total bytes, with zero total meaning unknown size. Counts reset on retries. Other stages report (0, 0). The existing runtime is checked before any network request or archive extraction.