Languages Cleanup Dashboard

Audit for `/24tb-1/languages`, `/24tb-2/languages`, `/24tb-3/languages` with focus on courses that include audio plus PDFs/books, plus separate tracking for video-heavy material.

Rules: symlink duplicates are skipped, scanned image books count as "book" if the folder has many images and no video, audio+book is the priority bucket, and "video courses" means folders with video that are not already in the audio+book bucket.