Settings > Performance > Thumbnail cache gets Choose Folder... / Use Library
Folder next to the size limit, backed by the new library.thumbnailCacheLocation
command. The folder is saved in prefs.json, must be absolute, and is checked
before anything moves; cached thumbnails are moved, left or deleted on a
change. A chosen folder missing when the library opens is reported and never
recreated (thumbnails stay in memory), and the disk cache no longer creates
missing parent folders.
Also switches one chunks_exact in spots.rs to as_chunks, which clippy 1.99
flags on main.
Fixes#903
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
