A maintenance job to keep the music library tidy — finds empty folders left behind
by imports/relocations/deletions (empty artist/album dirs, or dirs holding only OS
junk like .DS_Store/Thumbs.db) and removes them.
Safety is the focus (deleting directories is destructive):
- only TRULY empty folders are flagged — a folder with a cover image or any audio
is never touched; only OS-junk files count as "no real content" (a setting),
- the library root + symlinked dirs are never removed,
- walks bottom-up so a parent left empty by its removable children cascades,
- the apply handler RE-CHECKS emptiness at delete time, so a folder that gained a
file between scan and apply is left alone.
dir_is_removable + remove_empty_folder are pure/injectable seams. Wired through the
job registry, repair_worker apply handler (_fix_empty_folder), fixable-types, and
the findings UI. Opt-in (default off), weekly interval.
Tests (10): removable decision (empty / real-file / surviving-subdir / junk-only /
strict mode) + apply re-check (removes empty + junk, refuses content/root/symlink).
Repair + integrity suites green; ruff clean.
