Function crispasr_session_set_progress_callback 

pub unsafe extern "C" fn crispasr_session_set_progress_callback(
    s: *mut CrispasrSession,
    cb: CrispasrProgressCallback,
    user_data: *mut c_void,
)

0.10.3+ (issue #208): register a per-session progress callback for long-form (chunked) transcription. Fired once per finished window with (processed_samples, total_samples, user_data); processed is monotonic and reaches total on the last window. Invoked on the transcribe thread. Pass None/null cb to clear.